APPEAL COURT, HIGH COURT OF JUSTICIARY
Lord Justice Clerk
 HCJAC 30
Appeal Nos: XC463/03; XC462/03
OPINION OF THE COURT
delivered by THE LORD JUSTICE CLERK
THE REFERRALS by THE SCOTTISH CRIMINAL CASES REVIEW COMMISSION
in the cases of
STEVEN ALEXANDER ROBERT JOHNSTON
HER MAJESTY'S ADVOCATE
For the first appellant: Kerrigan QC, Gilbride;
For the second appellant; Burns QC, Shead;
For the Crown: Murphy QC AD, Miss Reville; Crown Agent
17 March 2006
 The appellants were tried at Edinburgh High Court in March 1996 on the following charge:
"Between 3 and 9 November 1995, both dates inclusive, at 38 Milton
Green, Dunfermline you Billy Allison and Steven Alexander Robert Johnston did assault Andrew Forsyth, residing there, punch and kick him repeatedly on the head and body, strike him repeatedly on the head and body with pieces of wood or similar objects, stab him on the body with a pair of scissors, compress his throat with your hands and did murder him."
In the course of the trial, and before defence evidence was led, the advocate depute amended the charge by deleting "between 3 and 9 November 1995, both dates inclusive" and substituting "on the 3 November 1995" and by deleting the words "stab him on the body with a pair of scissors." The amendment to the date libelled was critical. On 19 March 1996 both appellants were convicted by a majority verdict.
 The police enquiry in this case was carried out by officers of Fife Constabulary. Within about three days after the finding of Andrew Forsyth's body, D Insp Richard Munro became the senior investigating officer in charge of the enquiry. He and DS John Nessel were the reporting officers. In 2004 Mr Munro, by then D Supt, resigned from the force in advance of disciplinary proceedings unconnected with this case. It appears that DS Nessel is no longer serving with Fife Constabulary. His present whereabouts were not established at the hearing of evidence before us. The enquiry was directed from an incident room of which the officer in charge was D Insp Derek McEwan. He too has resigned from the force and now lives in Spain.
 The Scottish Criminal Cases Review Commission (the Commission) has referred the cases of both appellants. It considers that, by reason of the suppression of certain evidence by the police before the trial and in the light of new evidence obtained since then, there may have been a miscarriage of justice (cf Criminal Procedure (Scotland) Act 1995 (the 1995 Act), s 194C). The appellants have taken the opportunity to appeal in these proceedings (ibid, s 194B(1); Campbell v HM Adv, 2004 SCCR 220, at para ) on similar grounds.
II The background
 The deceased lived near Pittencrieff Park, Dunfermline, known locally as the Glen. He and the appellants were among a number of alcoholics who frequented the Glen and who used the deceased's flat as a drinking den. The deceased was well known and well liked in the neighbourhood. He had a gentle nature and was not a troublemaker. He had been the victim of violence on numerous occasions. He was easily recognisable by his red hair and his characteristic gait. The deceased was to have been a Crown witness in an impending trial of the appellant Allison and an associate, Colin Morrison, and had suffered violence and threats of violence on that account. At 10.20 pm on Thursday 9 November 1995 his mother found his body in his flat at the locus libelled. In the early hours of Friday 10 November, Professor Derrick Pounder of the Department of Forensic Medicine of the University of Dundee visited the scene.
III The trial
 The Crown case was that the appellants murdered the deceased on Friday 3 November. It is common ground that several witnesses saw the deceased alive in the course of that day. The defence case was that the appellants assaulted the deceased that day in a fight in which he suffered only a nose bleed and that he was alive and well as late as 7 November, and perhaps even in the early evening of 9 November.
The eye-witness evidence
Witnesses for the Crown
 There was no eye witness to the murder; but several witnesses implicated the appellants directly. Thomas McMullan said that he met the appellants in the evening of Friday 3 November. Both had blood on the legs of their jeans below the knees. Allison had blood on his white trainers. The witness went with Johnston to a public house where Johnston told him that he and Allison had given the deceased a "tanking" at his house. On Monday 6 November, Johnston told him that the deceased was dead. He said that he and Allison had given the deceased a "hammering" because he was a "grass." They had "gone over the score a bit" and had hit him with bits of furniture and an iron. They had returned to the house on Saturday 4 November for Allison's glasses but found only the frames.
 James Allan said that on Saturday 4 November while in the company of Allison, in a room occupied by George McCrorie, he had seen clothing which he recognised as Allison's. It included bloodstained denims with what seemed to be a lot of blood in the thigh area. Allison asked McCrorie to get rid of the clothing. Allison told this witness that he did not know with whom he had been fighting. Later that day, Allison asked the witness Gordon Shepherd (infra) to get his glasses from the deceased's flat. When Shepherd came back he said that he had seen the deceased lying in his flat and thought that he was dead. Allison did not react to this. Later, Johnston told this witness that he had been in a bit of bother the night before, that is to say 3 November, and said "I hope he's dead. I'll do 15 years for him." On Sunday 5 November the appellants came to his room. Outwith Johnston's presence, Allison said "We went back down there last night. Body was stiff as a board." Allan then gave Allison a spare pair of glasses.
 Samuel Edgar, a barman, said that on Friday 3 November Johnston had tried to set himself up as having been in his pub that day at 5 pm. Later that evening, when he was giving Johnston and Allison a lift, Johnston said "He'll not be there tomorrow" or "He'll no' survive until tomorrow" or words to that effect.
 Gordon Shepherd said that on Saturday 4 November Allison asked him to go to the deceased's flat and get his glasses back. When he looked through the window, he saw someone lying asleep on the floor and, from his red hair, he assumed that it was the deceased. He thought that he was asleep through drink or drugs. Later he thought that he might be dead. This witness conceded that at the time of these events he was in the middle of a "bender" and that he could not recall the precise day on which these events occurred.
 Richard Anderson said that on Saturday 4 November Johnston said "He was just a grass anyway" or words to that effect.
 James McDade said that on Saturday 4 November Johnston told him that he had been in a bad fight on the Friday night. At about 2.30-3.00 pm that day, this witness accompanied Shepherd to the deceased's flat and through the livingroom window saw a man lying on his back with his shirt up over the right side of his stomach. The witness could see no breathing movements.
 George McCrorie said that on the morning of Saturday 4 November Allison gave him a pair of jeans, a shirt and a jacket. Allison asked him to get rid of them. He noticed one or two spots of blood on one leg of the jeans. Allison's right hand was bruised around the knuckles. He was not wearing his glasses. This witness disposed of the clothes at a tip.
 PC John Mathieson's evidence supported the defence case. He said that on Tuesday 7 November, at about 6.35 pm, he went to the deceased's flat to deal with a report of a break-in. He shone his torch through the window. The room was illuminated by the torch and by light from the kitchen window. He did not see a body. The furniture in the room was not in the positions shown in the scene of crime photographs taken on 9 November.
Witnesses for the defence
 Allison said that he had had a fight with the deceased in his flat on Friday 3 November in which he burst the deceased's nose and caused it to bleed. The fight had lasted for two minutes at most. He had punched him three or four times on the face before Johnston broke up the fight. When Allison left the flat, the deceased was standing up and shouting at him. Allison admitted that he asked McCrorie to get rid of his clothes and that he lied to the police. He said that he did this because he was on bail at the time. He did not recall having met Thomas McMullan on 3 November. He claimed that he had drink-related blackouts. He had been unable to recall many details of what happened at the locus until Johnston refreshed his memory on the following day. He could remember the fight, but could not remember what it was about. He had seen someone at a distance on Monday 6 November near the library whom he thought was the deceased. He denied that he said that he had given the deceased a "tanking." He had said that he gave him a "leathering."
 Johnston said on 3 November there had been a minor fight in the deceased's flat between Allison and the deceased in which the deceased suffered a nose bleed. Johnston said that he broke up the fight. When he and Allison left, the deceased was on his feet and was shouting. He was alive and well, apart from the bloody nose. Johnston denied that he made the incriminating remarks attributed to him by the Crown witnesses.
 Eileen Thow said that she spoke briefly with the deceased at the Rendezvous Bar on the evening of Sunday 5 November.
 Mary Brockie said that in the morning of Monday 6 November she saw the deceased coming out of his flat in the company of a girl. She walked behind them into town.
 Janet Thow, Eileen Thow's mother, said that she was more than 50% sure that in the afternoon of Monday 6 November she saw the deceased from the window of her flat.
 James Drummond said that some time after 2 pm on Tuesday 7 November he and his wife saw the deceased in the Glen. His wife, Margaret Drummond, corroborated his evidence.
 Alan Henderson said that he saw the deceased walking in Nethertown Broad Street on the evening of either Tuesday 7 or Thursday 9 November. He was certain that this sighting had not taken place in the previous week.
 In Allison's case, the eye-witness evidence was supplemented by real evidence. His clothing was recovered from the tip. Blood found on the shirt and jacket did not belong to either of the appellants. It was highly probable that it was the blood of the deceased. The lenses of Allison's glasses were found in the deceased's flat. Footprints were found on a paper in the livingroom. They corresponded with Allison's trainers in terms of size, pattern and chance damage.
The pathologists' evidence
 Professor Pounder and Dr Diana Cox carried out a post mortem examination on behalf of the Crown on the morning of Friday, 10 November. Professor Anthony Busuttil of the Department of Forensic Medicine of the University of Edinburgh carried out a post mortem examination on behalf of the defence on Wednesday, 15 November.
 Professor Pounder and Professor Busuttil agreed that death was caused by blunt force head and neck trauma; but they differed as to the time of death. That question was critical because, as a result of the amendment to which we have referred, the advocate depute perilled the Crown case on proof that the murder was committed on 3 November and on no other date.
 The post mortem report of Professor Pounder and Dr Cox did not refer to time of death. At the trial, Professor Pounder estimated that death occurred between three days and a week before the body was discovered. His preference was for a time of death in the upper end of that range. He said that the time of death could have been up to two weeks before his post mortem. He preferred a time of death a week or so before the post mortem, rather than three days; but he could not discount the possibility that the death had occurred on 5 November. In cross-examination, he was asked if it were possible that the deceased could have been seen alive less than three days before the post-mortem. He replied that the chance of that was so remote that he would not consider it a serious possibility. Professor Pounder's estimate therefore supported the Crown case.
 From his post mortem examination, Professor Busuttil could not assess when death had occurred. He accepted that Professor Pounder had the advantage of him in that respect. From information provided by witnesses who had seen the body while it was at the locus and immediately afterwards, and from a perusal of Professor Pounder's notes, he considered that the death had occurred at least 24 hours before Professor Pounder's post mortem, but probably more than that. He considered that the body had certainly been dead for 36 hours before it was found and could have been dead for up to 48 hours. In his opinion, the deceased had been dead for about 2 days before his body was found, but certainly not for three or four. He was emphatic that the body had not been lying there for seven days. His estimate of the time of death was therefore incompatible with the Crown case.
The trial judge's directions
 There was plainly sufficient evidence to entitle the jury to convict both appellants. The trial judge directed the jury that the Crown case was that the appellants committed the murder on 3 November; that the evidence on which the Crown relied was tied to that date, and that, in consequence, the date of death was one of the essential facts. If the Crown did not prove beyond reasonable doubt that the deceased was killed on that date, its case failed and the appellants were entitled to be acquitted. The trial judge referred to the conflicting evidence of Professor Pounder and Professor Busuttil before again directing the jury that if, having weighed all the evidence, they had any reasonable doubt that the deceased had been killed on 3 November, the Crown had failed to prove its case.
IV Post-trial events
The first appellant's appeal against conviction
 The first appellant appealed against conviction on grounds that are not material to these proceedings. The appeal was refused (cf Johnston v HM Adv, 1997 SCCR 568).
Correspondence between the first appellant's solicitors and the Chief Constable and Crown Office
 In preparing for the trial Mr Stephen G Morrison, the first appellant's solicitor, discovered that the defence witnesses who claimed to have seen the deceased alive after 3 November had given information to that effect to the police during the course of the murder enquiry. Mr Morrison was concerned that the police had not conveyed this information to the procurator fiscal. After the trial he did not let the matter rest. He is to be commended for his professionalism. On 21 March 1996 he wrote to the Lord Advocate complaining about the conduct of the police. He copied the letter to the Chief Constable of Fife Constabulary. On 10 April 1996 Deputy Chief Constable Bennet sent the following reply.
"I refer to our previous correspondence and would advise you that I now have a report on this matter.
In this particular case there was more than sufficient evidence to establish the time of death of Mr Forsyth, and it was clear that any persons stating that they saw Mr Forsyth after 3rd November 1995 were clearly mistaken.
The Police alone did not simply form the view that Mr Forsyth was murdered on 3rd November. That belief was founded upon all the available evidence.
With regard to the penultimate paragraph of your letter, a response was forthcoming following a press release and, indeed, responses were obtained throughout the course of the enquiry. It became absolutely essential that any information gleaned was carefully considered and where necessary sifted and weeded.
During the course of any major enquiry much information is amassed. Such enquiry is wide-ranging and complex with teams of officers gathering and collating evidence. There is a need, therefore, for a senior officer to decide the course of enquiry, ensuring that all evidence pertinent to the enquiry is revealed to the Procurator Fiscal in order that he prepare his case.
In this particular case it became clear that the persons you name and indeed provided as witnesses were mistaken in their view and I am informed that their evidence was not readily accepted by the jury. Additionally, I am informed that the issues you raise were articulated during your client's trial and were not upheld by the trial judge.
In conclusion, it has always been the case that the Police have discretion to discount any course of enquiry. It is the duty of a senior officer, where information contrary to the real facts of the case is placed before him, to make a decision based on his knowledge of the case and his experience. It is important that he ensures that all material evidence is presented to the Procurator Fiscal in order that the latter can prepare his case.
I am satisfied that my officers adopted the correct course of action and sifted, despite your views, information which was unnecessary. This was based on experience of many years and there was most certainly no intent to suppress any significant evidence."
The report referred to in this letter has not been found in police files.
On 5 July 1996 Mr Norman McFadyen, the Deputy Crown Agent, replied as follows:
"I refer to previous correspondence and apologise for the delay in letting you have a substantive response to your letter of 21 March 1996 to the Lord Advocate, to which I have been asked to reply. You will appreciate, however, that enquiry required to be made of the Procurator Fiscal and by him of the Fife Constabulary.
I understand from the Procurator Fiscal that he was provided with all statements taken by the police in this case. These did not include statements of the defence witnesses in question and I understand that the police do not have a record of any statements having been taken from the defence witnesses. After the death of Andrew Forsyth the police conducted what amounted virtually to door to door enquiries which involved a very large number of persons being spoken to. I am advised that no details were retained of the results of any enquiries which were discounted during that process and, accordingly, statements were not prepared.
You will of course be aware of the duties of the police in investigating and reporting cases as described by Lord Justice-Clerk Thomson in Smith 1952 JC 66, including the power of selection in ensuring that evidence which is relevant and material is put before the Procurator Fiscal."
The second paragraph of this letter was based on untruthful information given by Fife Constabulary. The letter was also at odds with Deputy Chief Constable Bennet's letter. The third paragraph would perhaps have been better directed to the Deputy Chief Constable.
 On 17 July 1996 Mr Morrison again wrote to Crown Office with some further points. On 3 February 1997 the Deputy Crown Agent replied as follows:
"I refer to previous correspondence and in particular to the points raised by you in your letter of 17 July 1996.
In light of the experience of this case and consideration of the matters which were previously raised by you, the Regional Procurator Fiscal and District Procurator Fiscal arranged to meet the Deputy Chief Constable to discuss the lessons of the case and in order to ensure that the implications of Smith v HMA 1952 JC 66 were properly understood. Steps have been taken to ensure that there is no doubt about the proper relationship between the police and the Procurator Fiscal in this regard. The Lord Advocate and I are in no doubt that the information which was provided to the police by the witnesses in this case should indeed have been drawn to the attention of the Procurator Fiscal. That view is being made quite clear to the police at the highest possible level as also is the Lord Advocate's request that the issues which have arisen in this case be stressed in police training.
It will always be a matter for operational judgement in each investigation to what extent and in what form information conveyed, in particular during door to door type enquiries, should be recorded. In my letter of 5 July 1996 I informed you that I understood from the Procurator Fiscal that he was provided with all statements taken by the police in this case and that these did not include statements of the defence witnesses in question and that I understood that the police did not have a record of any statements having been taken from the defence witnesses. I conveyed that information to you on the basis of what the Procurator Fiscal had been told by the police. In the course of further discussions between the Regional Procurator Fiscal and the Procurator Fiscal and the Deputy Chief Constable this matter has been further explored and it is clear that the information which I gave you was inaccurate.
It is now clear that there was a limited computer record in respect of one witness, a notebook entry in respect of the account of another and a HOLMES computer record of the account of a third witness. While none of this material had been extended into statements for submission to the Procurator Fiscal it is now clear that the information which I previously conveyed to you in my letter of 5 July was inaccurate and misleading in relation to the retention of the results of enquiries by the police and the taking of statements. The Procurator Fiscal is satisfied that there was no intention on the part of the police deliberately to mislead him in this matter. The Lord Advocate has instructed that it be made clear to the Chief Constable that it is wholly unacceptable that misleading information was given to the Procurator Fiscal when these matters were raised. Needless to say, he very much regrets that any misleading information was conveyed to you.
As I hope I have made clear, lessons have, however, been learned from the investigation of this case."
 With this long-delayed letter the Deputy Crown Agent formally admitted that his letter of 5 July 1996 had been based on "inaccurate and misleading" information provided by Fife Constabulary. This letter, one might have thought, set the record straight and gave the first appellant the comfort of knowing that steps had been taken and lessons had been learned. Unfortunately, this letter too was based on false information given by Fife Constabulary. As we shall show, the fourth paragraph did not give a complete account of the information available to the police at the time of their report to the procurator fiscal, and in particular of the extent of the information contained in the HOLMES (Home Office Large and Major Enquiry System) computer record, which we shall describe later. But for the persistence of Mr Morrison this letter would have been the last word on the subject.
 By 2000 the Commission had begun its investigation. It learned from Crown Office that the witness in respect of whom there was a limited computer record was Margaret Drummond, that the witness in respect of whom there was a police notebook entry was Eileen Thow and that the witness in respect of whom there was a statement on the HOLMES computer record was James Drummond. Crown Office also disclosed that the existence of Eileen Thow, Janet Thow, Margaret Drummond, James Drummond and Mary Brockie was unknown to the procurator fiscal until the defence list of witnesses was intimated to him on 27 February 1996.
 The Commission then pursued its own investigations and discovered that, contrary to the Deputy Crown Agent's letter of 3 February 1997, the police had had information regarding no fewer than 11 potential witnesses to the fact that the deceased was alive after 3 November, namely Eileen Thow, Janet Thow, Mary Brockie, James Drummond, Margaret Drummond, Alan Henderson, Michael Healy, Karen Wheelwright, Mhairi Cormack, Robert Young and Michael Franklin. The evidence that we have heard shows that at that stage the police knew of other potential witnesses to that fact. Even after the Commission began its investigation the police rearguard action continued. An internal memorandum from D Supt Munro, as he had then become, to his colleague D Insp Watson was recovered by the Commission. It is date-stamped 14 November 2001. It is in the following terms.
"I think you should provide all reports to the PF but highlight that these were internal for police eyes only. You should make the point that when I and DS Nessell, as reporting officers took the papers to Mr Hamilton, PF, we informed him that there were a number of other peripheral witnesses which we did not consider worthy of inclusion at that time. He said that was fine and if necessary he could see them during police precognitions. No police officers were precognosced.
As outlined in the reports the witnesses that were known to me were not submitted for the reasons given. I have subsequently learned that other individuals have come to light but this was not known to the reporting officers at the time. Contact me if you require anything else.
PS It may be worth mentioning that these decisions were made in 1995, before the requirements of ECHR and in the absence of directions on disclosure."
In the second paragraph Mr Munro does not name the individuals to whom he is referring. From the history of the enquiry that we shall outline, we conclude that all relevant witnesses had come to the notice of the police before the case was reported to the procurator fiscal. Mr Munro could not assist us on this memorandum. He said that he had no recollection of it.
V The evidence heard by this court
(1) Evidence that the deceased was alive after 3 November
(a) Witnesses who gave evidence at the trial
 Eileen Thow spent Sunday 5 November 1995 with her fiancé David Guild and his friend Peter Weaver. In the afternoon they went to a meeting of amateur radio enthusiasts in Dundee. In the evening they went to the Glen to see a fireworks display. When they got there, the display was over. They then went to the Rendezvous Bar of which Eileen Thow's father, John Thow, was the licensee. Eileen Thow stood beside the deceased at the bar and spoke with him for some seconds. She then sat at a table facing the bar. She saw the deceased finish his drink and leave. Soon after fireworks night she spoke to the police at her home.
 Mary Brockie knew the deceased by sight. His flat was at the top of her street. On Monday 6 November she left her house at 10 am to go to the town centre. It was the morning after the fireworks display, which she remembered. When she got to the top of the street, the deceased came out of his door with a girl. The witness followed them all the way to the King's Gate Shopping Centre, a walk of about 121/2 minutes. She later saw the deceased and the girl at the top of King's Gate. The deceased was talking to friends. This evidence confirmed what Mrs Brockie had said in her door to door interview questionnaire, except that according to the questionnaire she said that she saw the deceased at 10.15 am.
 Janet Thow was the licensee of Jinty's Bar in Nethertown Broad Street, which was about two hundred yards from the deceased's flat. She knew the deceased well. He had a distinctive loping walk. In the afternoon of Monday 6 November between 1 pm and 3 pm she saw him from the window of her flat above the bar. He was on the other side of the street. She recognised him from his walk and from his clothing.
 James Drummond again spoke to the occasion on Tuesday 7 November when he and his wife walked through the Glen at about 2.10 pm and saw the deceased. Mrs Margaret Drummond gave evidence to the same effect. Both of these witnesses were confident of their identification of the deceased, whom they knew well.
 PC John Mathieson, now retired, confirmed the evidence that he gave at the trial that on Tuesday 7 November at about 6.35 pm he looked through the living room window of the flat and did not see a body.
 Alan Henderson was a part-time pools collector. He knew the deceased slightly. On Friday 10 November he went to the incident caravan and reported that on Thursday 9 November at 6.30 pm, while he was pools collecting, he had seen the deceased walking in Nethertown Broad Street. It dawned on him later in the week that he had also been collecting in that area on Tuesday 7 November. He confirmed the evidence that he had given at the trial to the effect that he saw the deceased on either of those dates. He remained certain that this sighting did not occur on the Thursday of the previous week. He was certain that it was the deceased whom he saw because he had a particularly clumsy walk and had red hair. He saw him from his car. He was driving slowly at the time because of roadworks.
 We found each of these witnesses to be credible and reliable. They were transparently honest people who tried to tell the truth to the best of their recollection. The only material point of uncertainty was in the evidence of Alan Henderson. We believe his evidence that he saw the deceased after 3 November; but, having regard to the pathologists' evidence, we think it more likely that it was on Tuesday 7, rather than Thursday 9, that he saw him.
(b) New witnesses
 Michael Healy owned a newsagent's shop in Woodmill Road, about one and a half miles from the deceased's flat. The deceased was an occasional customer. When this witness learned of his death, he remembered having seen the deceased in the shop on the morning of Saturday 4 November 1995 at about 6.30 am. He had reason to remember that it was a Saturday because he was putting magazine supplements into the newspapers. The deceased bought a newspaper and they had a conversation. The deceased had a mark next to his left eye.
 Mhairi Cormack was a senior housing officer with Dunfermline District Council. She had no recollection of having given a statement to the police on Friday 10 November 1995, but she accepted that what was recorded in the statement that bore to be hers accurately reflected what she had said at the time. According to a statement taken from this witness by WPC Amanda Givan on 10 November, she called at the deceased's flat at about 2.15 pm on Tuesday 7 November 1995. She was accompanied by a colleague, Robert Young. They were unable to get into the house. She looked in the livingroom window. It was daylight. She had a good view of the room and saw nothing suspicious. She did not see a body. Like Miss McCormack herself, we have no reason to think that what is recorded in the statement is not an accurate reflection of what she recalled at the time.
 Robert Young too looked in the window, which he mistakenly thought was the bedroom window. He definitely did not see a body, although he accepted that the light was not good.
 John Thow knew the deceased as an occasional customer at the Rendezvous Bar and at Jinty's Bar. When he learned of his death on Thursday 9 or Friday 10 November, he remembered that he had last seen him in Jinty's Bar on the morning of Friday 3 November. The deceased's face was uninjured. He told the police that Michael Franklin had told him that he had seen the deceased in Jinty's Bar in the afternoon of Wednesday 8 November.
 Michael Franklin is dead. In an affidavit dated 21 September 2001 he confirmed that he was with the deceased in Jinty's Bar in the early afternoon of Wednesday 8 November and spoke with him.
 Paul King is not mentioned in the Commission's referrals. He is imprisoned for a murder committed in December 1995. He said that the police interviewed him about the death of the deceased on Sunday 12 November. He had known the deceased since he was a boy. He remembered having seen him on Wednesday 8 November. He left work that day at 5 pm. Two or three minutes later, he saw the deceased in a telephone box in the High Street with Derek Mooney's girlfriend. She was drunk and was making a fool of herself. She was shouting and bawling at the deceased.
 Karen Wheelwright knew the deceased well. She was at school with his brother. She learned of his death from a television broadcast in which it was said that he had been murdered on 3 November. She realised that she had spoken to him after that date. She said that on 7, 8 or 9 November between 11.00 and 11.30 am, when she was on her way to work, she saw him standing at the corner of High Street saying cheerio to another male person. She spoke to him. This could not have taken place during the previous week. She was emphatic that whether it was on 7, 8 or 9 November, she saw him after the date given in the broadcast. She was interviewed by the police on Monday 13 November and gave this account.
(2) Evidence of the pathologists
 We have the impression that Professor Pounder's evidence before us on the question of time of death was more guarded than it was at the trial. He accepted that from the post mortem report one could conclude that the body had been dead for more than 24 hours. It followed, therefore, that signs of putrefaction gave the best indication of time of death; but the state of putrefaction was dependent on ambient temperatures. In attempting to reach a view as to time of death, he would ask the police for such information as they had as to when the deceased was last seen alive and when the body was found. This was because circumstantial evidence was often much better than medical evidence. The assessment of time of death depended largely on evidence of past sightings. He accepted that the estimation of time of death was not an exact science and that a reliable observation of the deceased alive would overturn any scientific opinion to the contrary. Whatever scientific inferences could be drawn from the state of putrefaction must yield to any contrary evidence based upon a reliable observation that the deceased was alive. If there was reliable evidence that the deceased was alive within three days of the post mortem, then, for whatever reason, the findings of the post mortem were anomalous. Experience had taught him that, even applying science, one could make an error over time of death. He said that he would find it difficult to accept that the deceased was seen alive on Wednesday 8 November; but that that was not impossible.
 Professor Pounder was emphatic that he did not express the view that the deceased died on 3 November. He said "I would never have pinned my colours to the mast and said that death occurred on 3 November." But by the time of the post mortem he believed that the police had concluded that that was the date of death. After the post mortem, the police did not return to him to ask for his view on the point in the light of further evidence.
 Professor Busuttil adhered to the opinion that he gave at the trial. Taking into account rigor mortis, putrefaction, the internal state of the body and the ambient temperature, he concluded that the deceased had been dead for between 24 and 48 hours before Professor Pounder's post mortem. He said that a sighting of the deceased alive on the afternoon of 8 November was "not impossible, but we're stretching it." The possibility of a sighting on 7 November was "much more likely." Sightings in the period 5 to 7 November were entirely consistent with his theory of time of death.
 Like Professor Pounder, Professor Busuttil accepted that in the inexact science of estimating time of death the pathologist should take into account reliable eye-witness evidence of sightings of the deceased and of the finding of the body. He positively excluded the possibility that death occurred on 3 November because that was inconsistent with the process of decomposition and with his own findings.
(3) Evidence about the police enquiry
 Although this is an appeal against conviction and not an inquiry into the conduct of the police, it is nevertheless necessary, for a proper understanding of the grounds of appeal, that we should set out in detail our findings as to the history of the enquiry and those aspects of it that have led to these referrals.
 Evidence about the police enquiry was given by seven police officers who took part in it; namely WPC, now WDC, Amanda Givan; DC, now D Insp, Kenneth Chatham; DC, now DC Insp, Colin Hershaw; DC, now DS, Lindsay Black; DC, now Insp, James McCluskey; DC, now Insp, Colin Caldwell, and the former D Insp Munro. We shall refer to these officers who are still in service by the ranks that they held at the time of the enquiry.
 We regret to say that we did not find Mr Munro to be a credible witness. He was taken point by point through the inadequacies and irregularities in the enquiry procedures. He was unable to give us a satisfactory explanation of any of them. He repeatedly dealt with counsel's questions by saying that he had no explanation to give; or that he could not recall what had happened; or that a particular irregularity was the fault of D Insp McEwan or of lower-ranking officers whom he was unable to name. In the result, he accepted no personal responsibility for any of the misconduct that this case has brought to light. Much of his evidence was untruthful, in our view.
 With the exception of WPC Givan, the other officers from the enquiry team who gave evidence did not impress us. There is no evidence directly implicating any of them individually in the suppression or alteration of statements; but, despite the senior ranks that some of them now hold, we were not satisfied that they told us the whole truth. It was our clear impression that they knew more than they were prepared to admit.
 WPC Givan, however, assisted the parties and the court by retrieving all of the information that can be found in the HOLMES records of the case. We accept her as a witness of credit whose only concern was to search for the truth.
 We also heard evidence from Alexandra Adamson, who was present when Karen Wheelwright gave her police statement, and from Robert Hamilton, who was procurator fiscal of Dunfermline at the time of the enquiry. Both of them were witnesses of obvious credibility and reliability.
VI The conduct of the police enquiry
 The enquiry used the original version of the HOLMES software. This system classifies the witnesses by serial number and creates for each a nominal record in which numbered actions and statements are recorded, priorities given to actions and statements are classified and cross-references are noted with other witnesses. When an action is initiated from the incident room and allocated to a specified officer, it is noted and timed and the result of it is added to the file. A statement taken in pursuance of an action is given to the receiver in the incident room and a printed version is thereafter entered in the system. A statement reader then decides what actions, if any, to raise in the light of it and classifies the priority to be given to it. The senior investigating officer (SIO) would not normally be working in the incident room or allocating actions. He would liaise with the officer in charge of the incident room, namely in this case D Insp McEwan. The SIO would give regular briefings to the enquiry team and to those in the incident room and report on progress.
 WPC Givan did not work in the incident room. She is an experienced trainer in the HOLMES system. She said that because the statements in this case had been dealt with under the original version of HOLMES, there was no audit trail as to who inputted the statements into the system. It had an audit trail for actions only.
 For the purposes of these referrals, the first significant stage in the enquiry was the post mortem. At the post mortem Professor Pounder and Dr Cox could not express an opinion as to the time of death. This is confirmed by a note in Mr Munro's handwriting that has been recovered from police files. It was made by him on information reported to him during or just after the post mortem. It contains the comment "no indication time of death." Professor Pounder requested that the police should obtain the average daily temperatures for Dunfermline for the period Tuesday 7 to Thursday 9 November, day and night. In the event, that information could not be obtained. Professor Pounder had to base the opinion that he gave at the trial on evidence that was later obtained of temperatures for that period in Dundee, which he considered to give a reasonable approximation.
 On 10 November the police set up a major incident enquiry. They brought an incident caravan to the locus and carried out house to house interviews. Despite the post mortem finding that there was no indication of time of death, the police committed themselves within 24 to 48 hours of the discovery of the body to the theory that the death occurred on Friday 3 November. They based this theory almost entirely on the information given to them by the drinking associates of the deceased whose evidence we have summarised. But, as is now agreed, numerous witnesses came to their notice who spoke to having seen the deceased alive after that date.
 Mr Munro at first told us that he believed that the police contacted the pathologists once they had information that the death took place on 3 November. That evidence was contradicted by Professor Pounder, it was not vouched by any contemporaneous document and we did not believe it. Mr Munro later said that he himself had not pursued the question with the pathologists, and could not say whether other officers did so. He did not know which officers would have dealt with that aspect. All the evidence establishes that the police did not consult the pathologists on the question of time of death at any time after the post mortem.
 On 10 November at 4 pm WPC Givan interviewed Mhairi Cormack. Miss Cormack gave the statement that we have summarised. In her HOLMES file, her statement was categorised as "low" priority. The action log shows that on 11 November the file was "resulted." Miss Cormack was not given a follow-up interview. Her colleague Robert Young was not cross referenced in Miss Cormack's file and he was not interviewed. Nothing was done in consequence of Miss Cormack's statement until 3 September 1996 when it was "filed." That was done at a time when the Crown Office was considering its reply to Mr Morrison's letter of 17 July 1996.
 Mr Munro was unable to explain any of this. He said that he did not deal with that matter himself. On the note of the police action in relation to Miss Cormack there is a handwritten note "NFA [sc no further action] meantime." Mr Munro suggested that the statement might have been filed because of an oversight on the part of D Insp McEwan. He said that he could not identify the handwriting on the note. He said that it must be that of someone in the incident room.
 On 10 November Mary Brockie was interviewed in the course of the house to house enquiry. She said that she had seen the deceased on Monday 6 November. Her completed house to house enquiry form was not entered in the HOLMES system. She was thereafter interviewed by the police; but there is no trace of her statement in police records. She was again interviewed on the eve of the trial by Mr Munro, as we shall relate.
 On the same day Alan Henderson gave a statement at the incident caravan that he had seen the deceased in Nethertown Broad Street at 6.30pm on 9 November. On 11 November an action (A51) was raised, with "high" priority, to take a statement from him. It was allocated to D Insp McEwan. On 16 November the action was completed and "resulted" without any statement having been taken. The action log print records "No further enquiries instructions SIO." Mr Munro explained that he made that decision in consultation with D Insp McEwan. He justified it by saying that he thought that Mr Henderson was "completely mistaken" because the pathologist had found at the locus that rigor mortis had set in. It seems not to have occurred to Mr Munro to investigate whether Mr Henderson might have seen the deceased in Nethertown Broad Street on any other evening of that week. Mr Henderson was not thereafter interviewed by the police; nor was he precognosced by the police in the days before the trial.
 On 10 November at 7.15 pm DC Hershaw took the statement of James Drummond, who said that he had seen the deceased on Tuesday 7 November in the circumstances that we have described. That statement was put into the HOLMES system. It was "filed" on 20 November.
 At the same time DC Hershaw interviewed Margaret Drummond. Some brief notes of the interview are in the HOLMES system under the description of a statement numbered S17. According to these notes, Mrs Drummond expressly referred to her sighting of the deceased in "the Glen," but this information was given a "low" priority. In the nominal record relating to Mrs Drummond (witness N76) there is noted "N76 describes deceased clothing - negative statement." Mrs Drummond's original police statement has not been found. It may have been recorded in DC Hershaw's notebook. Fife Constabulary were unable to provide the notebook when required to do so by the procurator fiscal.
 At about this time, Michael Franklin was interviewed in the course of the house to house enquiry. He told the police that he had been with the deceased in Jinty's Bar on Wednesday 8 November. The police hinted to him that he was probably mistaken about this. There is no trace of his house to house interview form in the police records. He was not interviewed thereafter.
 On Saturday 11 November at 11.40 am DC Chatham took a statement (S42) from John Thow, erroneously referred to in the statement as John Dow. This statement was in DC Chatham's handwriting. It was not signed by Mr Thow. In a paragraph at the end of it, Mr Thow said that Michael Franklin, a customer of Jinty's Bar, reckoned that the deceased was in the bar "early in the afternoon" of Wednesday 8 November. In a subsequent version of the statement put into the HOLMES system this paragraph was omitted. In its place there were substituted the words "I do not know the people responsible for killing Drew." This altered version of the statement was continued in the nominal record that was later prepared.
 Neither DC Chatham nor DC Hershaw could say why or by whom the handwritten statement of Mr Thow was altered. DC Chatham suggested that it would have been altered by someone at or above Inspector level. He said that after a statement was recorded by a police officer it could be changed only by, or on the initiative of, the officer in charge of the enquiry. He agreed with the suggestion of counsel for Johnston that Mr Munro appeared to be the prime suspect. He agreed that Mr Munro would have known how the statement had been doctored, if he was on top of his job. Mr Munro himself could offer no explanation. He said that he had learned of this irregularity only when he gave evidence before us.
 Mr Thow confirmed to us that he definitely told the police about the remark made to him by Michael Franklin. We believe him. On the other hand, he could not recall having said to them that he did not know who killed Drew. We do not believe that he said that.
 An action record was created for Michael Franklin. It was given "high" priority. It was cross-referenced to John Thow. On 11 November at 3.16 pm an action (A68) was raised by Mr Munro to "Contact N38 Franklin who may have seen the deceased drinking in Jinty's about 1345 hrs on Wednesday 081195." On 16 November at 2.13 pm it was "changed to for (sic) allocation 1 priority 1" and allocated to D Insp McEwan. The action was "completed" at the same time and was "resulted" at 2.14 pm. At the same time the HOLMES record was "filed." Although these times may be artificial, since the HOLMES record may have been created retrospectively, it is clear that a decision was made not to follow up the lead relating to Michael Franklin. The action log print records "No further enquiries instructions SIO." DC Chatham could not explain why the action on Michael Franklin was cancelled so promptly. Mr Munro said that he had no knowledge of that decision and had no recollection of the instruction.
 In the action record print relating to Michael Franklin, his possible sighting of the deceased early in the afternoon of 8 November is timed at "about 1345 hrs." Neither Mr Munro nor DC Chatham could explain where this timing came from. There is nothing in the HOLMES record to show its source.
 Janet Thow gave a statement to the police at about the same time as her husband about her sighting of the deceased on 6 November. There is no trace of it in the police files. There is no nominal record for Mrs Thow in the HOLMES system.
 As a result of the statements of John and Janet Thow, it came to the notice of the police that their daughter Eileen Thow had relevant evidence to give. Eileen Thow gave a statement to the police some days after her parents. The significance of it was unmistakable. She had reason to remember that she had seen the deceased in the Rendezvous Bar on the night of Sunday 5 November. She could relate that to her visit to Dundee and to the fireworks display in the Glen. The date and time of her visit to Dundee and her presence in the Rendezvous Bar on the same evening could easily be corroborated. There is no HOLMES record for Miss Thow and no trace of her statement. Mr Munro was unable to explain this. He said that other officers must have failed to put her statement into the system.
 On Sunday 12 November DC McCluskey in response to an action (A13) raised on 11 November, and on 12 November raised to "priority 1," took a statement in his own handwriting from Paul King at Dunfermline Police Station in the presence of PC Tait. The statement was unsigned. It recorded King as having said that he had seen the deceased about a week earlier, that he could not remember the exact date and that he had seen him at the phone boxes near Guildhall Street "with Diane (witness Kellock)." In the printed version of the statement, that appeared as "with Diane (Colin Morrison's girlfriend)." In the handwritten version the final sentences were
"I think China's first name is Steve. I don't know his surname. I don't know where he lives now. I do not know who would murder Drew and cannot think of any reason someone would have any reason to do so."
In the printed version these were deleted and there were substituted the words "I can identify China (accused Johnston)." No further action was taken on King's statement. Diana Kellock was not cross-referenced in King's HOLMES file.
 On Monday 13 November at 11.35 am DC Black and a colleague took a statement, in DC Black's handwriting, from Karen Wheelwright in the presence of her employer, Alexandra Adamson. Miss Wheelwright said that she saw the deceased between 11.00-11.30 am on Thursday 9 November, or possibly on Tuesday 7 or Wednesday 8; but not during the previous week. She said that "it was definitely Drew." There is no reference in her police statement to her having spoken with the deceased on that occasion. Miss Wheelwright said that both officers expressed surprise at what she said. They suggested to her that she could not have seen the deceased when she said she did. Alexandra Adamson corroborated her evidence on this point.
 The printed version of Miss Wheelwright's statement recovered from the HOLMES system has been edited. Certain words have been scored out. DC Black reported inter alia that a full statement had been noted from her regarding a sighting of the deceased "last week;" but the nominal record for this witness under the heading of cross references says "Alleged sighting of [deceased] 09.11.95 unmarked facially, nothing relevant." DC Black said that he did not make that entry in the nominal record. He agreed that the alleged sighting was relevant. Mr Munro said that he had no knowledge of Miss Wheelwright's statement.
 Karen Wheelwright was not re-interviewed. In the handwritten statement DC Black had noted Alexandra Adamson's particulars. That lead was not followed up. In Karen Wheelwright's HOLMES file there is no cross reference to Alexandra Adamson.
 By letter dated 14 November Mr Hamilton instructed that all statements in the case should be submitted to him within five days from that date.
 Thursday 16 November at 1.05 pm Michael Healy telephoned the police and told them that he had seen the deceased in his shop on 4 November 1995 at about 6.30 am. DC McCluskey took a statement (S97) in his own handwriting from Mr Healy at 5.15 pm that day. In it Mr Healy confirmed that he saw the deceased on Saturday 4 November. He said that it was possible he might be mistaken, but that he did not think so. The nominal record relating to this witness, under cross references, has the entry "S97: N151 [Healy] gives negative statement not required as witness." No police witness suggested that Mr Healy's statement could properly be described as negative. Mr Munro could not identify the author of this entry. He suggested that it might be the statement reader in the incident room or the officer in charge of the incident room. No further action was taken in relation to this witness.
 Meanwhile, on 14 November an action (A152) was raised and allocated to DC Chatham and DC Broadley to re-interview Margaret Drummond "specifically in regard to the movements of [the deceased] on 03111995." The following result of it is noted in the handwriting of WDC Beveridge "Drummond re-interviewed - no need for further statement - nothing further learned other than she may be mistaken by the sighting of the victim on Tuesday (7/11/95)." There is no statement of Mrs Drummond relating to this re-interview. It is only from DC Hershaw's and WDC Beveridge's notes that one has any record of her having said that she saw the deceased on 7 November. That sighting is not recorded in the nominal record itself.
 On 17 November an action (A153) dated 14 November to "re-interview James Drummond N17 specifically in relation to the movements of [the deceased] 03111995" was re-allocated to WDC Beveridge and DC Beattie and completed on 21 November. That resulted in a further unsigned statement by James Drummond dated 21 November (S10A) in which he is recorded as having said of the sighting on 7 November "It was then I thought I saw [the deceased] in the park, but I cannot be sure." Mr Munro concluded that this statement "cast doubt on his veracity." When Mr Munro and other officers saw this statement they decided that Mr Drummond had been mistaken. The statement was classified as "Noted not required for court purposes" and was filed. DC Hershaw said that the decision to file it would be taken by Mr Munro. In the nominal record itself there is no mention of a sighting by Mr Drummond on 7 November.
 At about this time, Mr Munro drafted his own witness statement setting out the background to the crime, the discovery of the body and the course of the enquiry. He did not mention any reported sightings of the deceased after 3 November.
 Mr Munro failed to meet the procurator fiscal's deadline for submission of all statements in the case. By letter dated 22 November addressed to the Detective Chief Superintendent, Western Division, Dunfermline, he submitted "all the full statements so far available." Since it was obvious that he did no such thing, Mr Munro explained to us that by that he meant "all the full statements so far as relevant." He and DS Nessel then took the statements to the procurator fiscal and discussed the case with him.
 The statements submitted with the letter included only one by a witness whose evidence suggested that the deceased was alive after 3 November, namely John Thow; but his statement was the fabricated version from which the reference to Franklin's sighting had been excised. Along with the statements Mr Munro and DS Nessel submitted a list of witnesses with a brief note of the significance of each witness's evidence. Beside the name of John Thow, referred to as John Dow, the note was "Last saw deceased in his public house on 031195."
 Mr Munro admitted that he withheld the statements of John Drummond and Alan Henderson. He said that he did so because "they were mistaken." He said that he had no knowledge of any other statement that suggested that the deceased was alive after 3 November. We do not believe that.
 Mr Hamilton sent the police witness list to the defence agents with the side notes blanked out. He confirmed that he was not made aware of any evidence that the deceased was alive after 3 November. He said that, if he had been, he would have reported the matter to Crown Office for instructions. The straightforward conclusion that we draw is that he was prevented from knowing that the date of death was even an issue in the case.
 On 27 February 1996 the defence intimated a list of the six witnesses to whose evidence at the trial we have referred. The procurator fiscal instructed the police to obtain statements from each of them.
 On 29 February 1996 at Jinty's Bar at 2.15 pm DC Chatham and DC Caldwell took a statement from Janet Thow in which she spoke of having seen the deceased on 6 November. At 2.25 pm DC Chatham took a statement from Eileen Thow. In it she described her meeting with the deceased on 5 November. She said that she had spent that day with David Guild and Peter Weaver. At 2.35 pm DC Chatham took a statement from David Guild. In it David Guild confirmed that he had been to Dundee with Eileen Thow and Peter Weaver that day and had been at the Rendezvous Bar when Eileen Thow brought them drinks from the bar. At 2.55 pm DC Chatham took a statement from Alexander Hynd at his home in the presence of DC Caldwell. In it Alexander Hynd said inter alia that he had been with Eileen Thow, David Guild and Peter Weaver at Eileen Thow's house on 5 November and that they left him at about 7 pm to go to the fireworks display.
 None of these statements was signed. This was the first time that the police had obtained corroboration of Eileen Thow's evidence about her movements on 5 November.
 On the same day, Mr Munro took a statement from Mary Brockie. He was not accompanied by another officer. In it he recorded Mrs Brockie as having said "I did not know Drew Forsyth either to speak to or by sight." Mrs Brockie denied having said this. She said that that was plainly wrong. Mr Munro also recorded Mrs Brockie as having said:
"That day I was in the shop opposite talking to Margaret Drummond (witness) when I told her I didn't know who the person was who had been murdered. She described him to me and I said I thought I had maybe seen him going to the shop for a paper. I then told her that it was maybe the same person I had seen coming out of the house on the Monday (6 November 1995)."
Mrs Brockie said that that too was wrong because she knew that it was the deceased. We believe Mrs Brockie. In our view, this was Mr Munro's version of what he wished her evidence to be. This statement was not entered in the HOLMES system. It may be contrasted with Mrs Brockie's evidence at the trial. In her evidence in chief, she was clear that it was the deceased whom she saw. She said "I'm, I'm one hundred per cent it was Andrew." She rejected the suggestion in cross-examination that she was mistaken.
 On 29 February 1996, a third statement was taken from James Drummond. The document relating to it bears to be timed at 7.15 pm on 10 November 1995 and 29 February 1996, and to have been taken by DC Hershaw and Mr Munro. It is in fact a composite document based on the statement taken by DC Hershaw on 10 November (supra) and on an interview conducted by Mr Munro on 29 February. By the latter date, it seems, Mr Munro was convinced that Mr Drummond was mistaken in his recollection of having seen the deceased on 7 November. This third purported statement, which is not signed by Mr Drummond, ends with a passage obviously written by Mr Munro which attributes to Mr Drummond the words "I told the police I thought I'd seen [the deceased] on 7 November 1995, but I cannot now be sure." The transcript of Mr Drummond's evidence at the trial has not been found.
 On 1 March 1996 DC Chatham in the presence of DC Caldwell took a statement from Margaret Drummond in which she again spoke to having seen the deceased on Tuesday 7 November. It includes the words "I cannot be 100% sure that it was Drew." Mrs Drummond did not sign this statement. It too can be contrasted with her evidence at the trial in which she was clear that it was the deceased whom she saw. She said that there was no doubt in her mind. She rejected the suggestion in cross-examination that she was mistaken. When asked if she "admitted of the possibility" that she could be wrong, she said that there was a "minute possibility" that she made a mistake, but that it was "unlikely."
 The police did not take a statement from Alan Henderson.
The scope of the appeal
 The statutory ground on which the Commission has referred the case (1995 Act, s 194C) reflects the fact that there is now one general ground of appeal, namely miscarriage of justice (1995 Act, s 106(3)). This ground may take many specific forms, such as misdirection of the jury, wrongful admission or exclusion of evidence or procedural irregularity. Section 106(3) refers to two specific grounds of appeal, namely fresh evidence (1995 Act s 106(3)(a)) and unreasonable verdict (s 106(3)(b)); but these are not independent grounds. They are merely instances of ways in which a miscarriage of justice may be alleged to have occurred.
 The advocate depute approached this case on the basis that in both aspects it was a fresh evidence appeal, the fresh evidence being that of eye witnesses on the question of the date of death; the documentary evidence recovered from police files, and the oral evidence of certain officers concerning the conduct of the enquiry. He submitted that all of this evidence, even if it had been available to the jury, would not have outweighed the compelling evidence of the appellants' guilt; and, in any event, that all of it when taken together did not compel us to conclude that the verdict must be regarded as a miscarriage of justice.
 In our opinion, the advocate depute's submission is based upon an incomplete view of the case. The appellants have tabled an appeal on the ground of fresh evidence; but they have also tabled a separate ground that is foreshadowed in the referrals, namely that the misconduct of the police deprived them of a fair trial and accordingly caused a miscarriage of justice. They have led an impressive body of new as well as previously heard evidence of the fact that the deceased was alive after 3 November. That was the central line of defence at the trial. But the appellants have also led evidence relating to the conduct of the police investigation. The evidence on this point is in a sense fresh evidence; but it is not evidence on the issue in the indictment. It is evidence as to the separate issue of the fairness of the trial (cf McPhee v HM Adv, unrepd, 6 December 2005).
Fresh evidence as to the date of death
 The question whether the deceased was murdered on 3 November or was alive after that date was a classic jury question (cf King v HM Adv, 1999 SCCR 330; Roy Dickson Smith v HM Adv, unrepd, 19 January 2005). It is not suggested that, on the evidence led at the trial, the jury returned a verdict that no reasonable jury, properly directed, could have returned (1995 Act, s 106(3)(b)).
 An appeal of this kind should be concerned with new evidence rather than with a repetition of evidence given at the trial. In our view, the evidence that we heard from PC Mathieson and the six defence witnesses who gave evidence at the trial, so far as it related to the time of death, was simply their previous evidence in an expanded form. It was not "evidence which was not heard at the original proceedings" (s 106(3)(a)); and for that reason alone it cannot found an appeal.
 In any event, in relation to the trial witnesses it is not for us to usurp the function of the jury. It is not our assessment of these witnesses that matters. The evidence of PC Mathieson and the six defence witnesses appeared to us to be credible and reliable; but we did not hear all of the evidence on which the Crown relied at the trial, nor did we hear the evidence of the appellants themselves. We are therefore not in as good a position as the jury were in to assess the overall impact of the whole evidence in the trial. The jury preferred the evidence for the Crown to that for the defence. It was for the jury to make such a judgment on the basis of their own appraisal of the evidence. In the circumstances, it would be a discourtesy on our part to express an opinion one way or the other on the jury's verdict.
 Nevertheless, the evidence of those witnesses has helped us to assess the impact that the new evidence would have had upon the jury if it too had been heard; and certain of those witnesses have given crucial new evidence on the separate issue of police misconduct.
 In our view, this ground of appeal must be decided on the evidence of the new witnesses indicating that the deceased was alive after 3 November. That is significant evidence having a direct bearing on a critical issue at the trial. In our view, it was capable of being accepted by a reasonable jury as being both credible and reliable. The Crown concedes that there is a reasonable explanation why it was not given at the trial (s 106(3)(a); (3A)). The question is whether it is of such significance that we may reasonably conclude that a verdict returned in ignorance of its existence "must" be regarded as a miscarriage of justice (Cameron v HM Adv, 1987 SCCR 608, Lord Justice General Emslie at pp 618-619; cf Kidd v HM Adv, 2000 SCCR 513, at paras -).
 The advocate depute submitted that the new witnesses merely added further evidence on an issue that the defence brought out at the trial, was the subject of considerable evidence and was identified as a decisive issue in the trial judge's charge. Since there were seven witnesses at the trial to the fact that the deceased was alive after 3 November 1995, the defence case on the point was squarely before the jury and must be held to have been rejected by them in the light of the evidence of the assault on the deceased on that day and Professor Pounder's evidence about the time of death. Of the trial witnesses who spoke to having seen the deceased after 3 November none was more compelling than Eileen Thow. She was the only one who claimed to have spoken to him. Her evidence pinpointing 5 November as the date of the conversation was strongly corroborated. Despite her evidence, the jury convicted. It was unlikely that the new evidence would have added any further strength to the defence case. In view of the compelling evidence that the appellants committed the murder on 3 November, it could not be said that a verdict returned in ignorance of the new evidence must be regarded as a miscarriage of justice.
 Counsel for the appellants submitted that the sheer volume of the additional evidence, when added to the defence evidence led at the trial, and the credibility and reliability of the witnesses who gave it, were such that the test in Cameron (supra) was met.
 In view of Paul King's demeanour in the witness box and the inconsistency between his evidence and his police statement as to the date on which he saw the deceased and as to the identity of the girl who was with the deceased, we did not accept him as a credible witness. Counsel for the appellants did not rely on his evidence and we need not consider it further. However, we considered that the other new witnesses were respectable and honest people on whose evidence we could rely. Their evidence satisfied us that the deceased was not murdered on 3 November. The only point of material uncertainty was in the evidence of Karen Wheelwright as to the date on which she saw the deceased. We believe her evidence that she saw him after 3 November; but, having regard to the pathologists' evidence, we think that that sighting cannot have been on 9 November.
 Two sources of evidence raised special considerations, namely the evidence of Mhairi Cormack and the affidavit of Michael Franklin. Miss Cormack was unable to recall any of the matters mentioned in her statement to the police; but she was emphatic that the statement that she made at the time was an accurate account of what she had seen and done at the locus, and she was content to adopt it as her evidence. Her account was supported by Robert Young whose evidence we accept. Michael Franklin's affidavit is admissible as evidence of what it contains (1995 Act, s 259(1)(a), 2(a)). It is supported by the evidence of John Thow, which we accept. We therefore accept the accounts set out in Miss Cormack's statement and Mr Franklin's affidavit as being true and accurate.
 Our conclusions on the new evidence are that Michael Healy spoke with the deceased on 4 November; that Karen Wheelwright spoke with him in the morning of 7 or 8 November; that Michael Franklin spoke with him in the early afternoon of 8 November; and that when Mhairi Cormack and Robert Young looked into the deceased's flat on 7 November, he was not there.
 Those are our own conclusions; but the critical question is what effect this evidence would have had on the minds of the jury if they had heard it. In our opinion, the new evidence would have greatly increased the strength of the defence case. We incline to think that the more evidence the jury had heard as to the deceased's having been alive after 3 November, the greater would have been the likelihood of an acquittal.
 We do not accept the submission of the advocate depute that the new evidence was merely more of the same. It had a special significance of its own. Of the six trial witnesses who said that they saw the deceased alive after 3 November, only Eileen Thow had been close enough to speak to him; whereas of the four new witnesses who said that they saw him after that date, three, namely Michael Healy, Karen Wheelwright and Michael Franklin, had spoken to him. The new evidence is therefore much stronger in this respect. Karen Wheelwright's credibility and reliability would have been supported to some extent by Alexandra Adamson.
 Moreover, if the jury had heard the evidence of Michael Healy, Karen Wheelwright, Michael Franklin, Mhairi Cormack and Robert Young, they would have been bound to see that, like that of PC Mathieson and the six defence witnesses whose evidence they heard, it came from honest, decent people who had no motive to tell anything but the whole truth. The likelihood that all twelve of these witnesses were mistaken would have been difficult for the jury to accept. If all of this evidence had been led, it would have had a vital bearing on the question of reasonable doubt as to the date of death, on which the trial judge had specifically directed the jury.
 The evidence of Miss Cormack and Mr Young would have also have been significant in relation to other evidence. They supported the view that the deceased was alive in the afternoon of Monday 7 November; but they also supported the view that he was out of doors that day around the time at which James and Margaret Drummond said that they saw him in the Glen. They also supported the evidence of PC Mathieson that there was no body to be seen in the flat about four hours later.
 Furthermore, in the light of John Thow's evidence that the deceased's face was uninjured when he saw him on the morning of Friday 3 November, Michael Healy's evidence that on the morning of Saturday 4 November the deceased had a mark next to his left eye would have supported the defence case that a minor fight had taken place at the deceased's flat on the previous night.
 We are confirmed in these conclusions by the evidence that we heard from Professor Pounder and Professor Busuttil. In our opinion, all of the new evidence would have been powerfully supported by Professor Busuttil's opinion that death occurred after 3 November. Furthermore, if that evidence had been led, Professor Pounder, as we now know, would have accepted in relation to it that the post mortem signs of time of death must yield to credible evidence of eye-witnesses who saw the deceased alive after that time, however anomalous the post mortem findings might then seem.
 In our opinion, the strength of the new evidence is such that we may justifiably conclude that a verdict returned in ignorance of it constituted a miscarriage of justice.
 Counsel for the appellants submitted that by improperly suppressing material evidence concerning the time of death, the police prevented the defence from putting forward their strongest case and restricted their cross-examination of Crown witnesses regarding the conduct of the enquiry. The advocate depute said that he wished to make no submission as to the conduct of the police other than to say that the full explanation of the suppression and alteration of evidence had yet to come to light and that the Crown did not regard that matter as closed. He relied on his basic submission that it had not been shown that the availability of the missing evidence would have materially affected the outcome of the trial.
 In the Scottish system of criminal investigation the procurator fiscal directs the investigation and not the police. In the early stages of an investigation, the police almost always act on their own initiative; but it is their duty to report on their investigation to the procurator fiscal and to act upon his further instructions. They have no authority to be selective in the potentially relevant information that they report, or to substitute their own judgment for that of the procurator fiscal as to the significance or otherwise of information that has a bearing on the charge.
 Although the Crown's obligation of disclosure of evidence is more formally regulated now than it was at the time of this enquiry, the obligation itself is of long standing. It is based on the principle that in the interests of justice the defence should not be kept in ignorance of evidence that could assist its case. An aspect of this principle is the long-established practice by which prosecutors lead evidence that may be unfavourable to the Crown case where it is relevant to the issue. If the Crown had known of the witnesses whose evidence was withheld from it, those witnesses would undoubtedly have been on the Crown list.
 If the police had reported fully on the question of time of death, the Crown might well have retained the latitude taken in the charge in its original form; but in that event the defence might have been in a strong position to suggest that there was no evidence of an assault on the deceased by either of the appellants on any date after 3 November.
 The Commission has reached the following conclusion in both referrals.
"In all the circumstances the Commission has found it difficult to conclude other than that the police took it upon themselves to filter out the existence of witnesses whose evidence might point to the deceased having been alive after November 3. These actions prevented the Crown from obtaining a complete picture of the movements of the deceased in the time immediately prior to his death, a picture which might have altered the way in which the case was prosecuted. The Commission also believes that the defence put forward on behalf of [the appellant] would have been presented in different terms had counsel been aware of the full extent of the sightings of the deceased after 3 November. These actions by the police resulted in the jury not being made aware of the full time scale and range of movements of the deceased in the days immediately following the supposed date of his death."
 At an early stage in their enquiries, and mainly on the word of certain unsatisfactory witnesses, the enquiry team decided that the murder had been committed on Friday 3 November. Thereafter they obstinately rejected all evidence that did not fit their theory. They did so despite the mounting body of evidence of later sightings of the deceased by credible witnesses. They decided that any witness whose evidence did not fit their theory must be mistaken. As more and more evidence emerged of sightings of the deceased after 3 November, the police refrained from seeking expert advice from Professor Pounder on the question of time of death. They also refrained from pursuing certain obvious and necessary enquiries with other witnesses who might support the possibility that the deceased was alive after 3 November.
 The misguided attitude of the police is well illustrated in the letter dated 10 April 1996 from Deputy Chief Constable Bennet to Johnston's solicitor which we have quoted. The advocate depute accepted that that letter showed a complete misunderstanding of the duties of the police.
 But the conduct of the police went beyond obstinacy. They suppressed and altered evidence casting doubt on their theory of the date of death. When they reported the case to the procurator fiscal, they suppressed the statements of Mhairi Cormack, James Drummond, Margaret Drummond, Karen Wheelwright and Michael Healy; they submitted altered versions of the statements of John Thow and Paul King; they falsified John Thow's statement by excluding the crucial reference to Michael Franklin; they did not mention the information that had been given to them in various forms by Mary Brockie, Alan Henderson, Janet Thow, Eileen Thow and Michael Franklin indicating that the deceased was alive after 3 November; and they did not mention that Robert Young and Alexandra Adamson were potential witnesses on that issue. It was the duty of the reporting officers to submit all of this information to the procurator fiscal. In the result, their report contained only one statement, that of PC Mathieson, that could be thought to raise a question as to the date of death; but that statement did not relate to a positive sighting of the deceased and, in the context of the other evidence, did not exclude the possibility that the deceased was lying dead in the flat at the material time. The evidence suppressed by the police was vital. The suppression of it was improper.
 Thereafter, when the defence intimated certain witnesses who would speak to the deceased's having been alive after 3 November, the police attempted to cast doubt on their reliability and in at least one case, that of Mary Brockie, Mr Munro attributed to her a statement that she obviously did not make.
 The police misconduct did not end with the trial. Fife Constabulary continued to mislead Crown Office in relation to the Deputy Crown Agent's letters of 5 July 1996 and 3 February 1997.
 In the letter of 3 February the Deputy Crown Agent said that the procurator fiscal was satisfied that there was no intention on the part of the police deliberately to mislead him. That is not our conclusion. On the fuller information available to us, we conclude that the police deliberately misled the Crown in a serious way. The result was that the procurator fiscal, and in consequence the defence, were kept unaware of evidence having a material bearing on a vital issue. The police thereby induced the Crown to adopt the police theory of the date of the murder and to challenge the credibility and reliability of any defence witness who cast doubt on it. That, in our opinion, was grave misconduct.
 However, for the purposes of these references, it is sufficient for us to say that the appellants were deprived of the opportunity to lead all of the evidence that would have been favourable to their defence and of arguing its full significance before the jury. They were therefore deprived of a fair trial. In this respect, too, they suffered a miscarriage of justice.
 We shall allow both appeals and quash the convictions and the sentences.