Here is the full judgement of the Privy Council (four pages):
1. On 29 May 1995, following a trial before Williamson J and a jury, the appellant David Cullen Bain was convicted on each of five counts of murder. As more fully narrated below, his appeals against those convictions have failed. He now appeals to the Board against the convictions under section 385(1)(c) of the Crimes Act 1961. He contends, in the light of fresh evidence which was not before the trial jury, that if that jury had had the opportunity to consider the case with the benefit of that fresh evidence they might reasonably have reached different conclusions. The convictions should accordingly be quashed and a retrial ordered. The Crown strongly resists that contention.
2. On 20 June 1994, when these five killings occurred, David was a 22-year old student studying music and classics at the University of Otago. Each of the counts related to a member of David's immediate family: his father Robin; his mother Margaret; his sisters Arawa and Laniet; and his younger brother Stephen. Robin, aged 58, was the principal of Taieri Mouth Primary School, a two-teacher school about 50 kilometres down the coast from Dunedin. Margaret, 50, did not work; she had (with Robin) been a missionary in Papua New Guinea, but her beliefs appeared latterly to have inclined towards the occult. Arawa, 19, attended a teachers' training college. Laniet, 18, had lived away from home for a period but had returned to the family home for the weekend. Stephen, 14, was still at school.
3. Robin spent three nights a week at Taieri, initially sleeping in the back of his van but more recently in the schoolhouse. He and Margaret were estranged, and on returning to the family home at the weekend and on Monday nights he lived in a caravan in the garden. Laniet had lived for a time in a flat in Dunedin and then with her father in the Taieri schoolhouse.
4. The family home was at 65 Every Street, Dunedin. It was an old, semi-derelict, wooden house, which was deliberately burned down shortly after the deaths. Internally, as is clear from the evidence at the trial and contemporary photographs, most of the rooms were dirty, squalid and very disorderly. They, and the caravan, contained large quantities of the family's belongings in disordered heaps.
5. The house faced south on to Every Street. It was on two levels, and was well set back from the road. The front door was in the middle of the front of the house at ground level. On entering the house through the front door, the visitor would enter a hallway. To his immediate right was the lounge, which had some chairs and occasional tables. To one side of this room was a curtained alcove. It was in this living room that Robin was shot. Opposite this room, across the hallway, was David's room, to the visitor's left on entering the house. Immediately next to David's room, on the left of the hallway, were steps down to the lower level of the house. Continuing down the hallway past the stairs, the visitor would come, on the right, to Margaret's bedroom, from which Stephen's room led off. On the left the visitor would come to the room where Laniet was sleeping at the time of the deaths, and beyond that to a living room which plays no part in the story. If the visitor were to go down the stairs to the lower level he would find three rooms: Arawa's bedroom; a kitchen; and a bathroom/lavatory in which the washing machine and a dirty clothes basket were kept. A door on the western side gave access to the house at this level.
The competing cases at trial
6. The Crown case against David, as developed at trial, was in very bare outline to this effect. At about 5.0 am or earlier on the morning of Monday 20 June 1994 David got up and dressed. He took from his wardrobe his .22 calibre Winchester semi-automatic rifle and unlocked the trigger lock with a spare key which he kept in a jar on his desk. He usually used a key tied on a string round his neck, but he had taken this off on Sunday 19 June when he took part in a polar plunge and had left it in the pocket of an anorak in Robin's van. He took ammunition from the wardrobe. He then shot and killed, in an unknown order, his mother, his two sisters and his brother. There was a violent struggle with Stephen, who was part strangled as well as shot, and during the struggle a lens of the glasses which David was wearing fell out in Stephen's room. These killings, particularly those of Laniet and Stephen, were very sanguinary, and as a result David's person and clothing became stained with blood. He therefore washed and changed his clothing, leaving marks in the bathroom/laundryroom, and put his blood-stained clothing in the washing-machine, which he started. Then, as was his normal practice, he set off at about 5.45 am to deliver newspapers. He did this rather more quickly than usual, returning home at about 6.42 am. He then went upstairs to the lounge and switched on the computer at 6.44 am, either then or at some later time typing in a message "SORRY, YOU ARE THE ONLY ONE WHO DESERVED TO STAY". David knew that it was his father's practice, some time before or after 7.0 am, to come in from the caravan and go to the lounge to pray. So he waited with the loaded rifle in the alcove off the lounge and, when his father entered the room and knelt to pray, shot him from very close range in the head. He then arranged the scene to make it look like suicide, and after a pause, rang the emergency services to report the killings, pretending to be in a state of great distress.
7. David's account was that he got up at the usual time, put on running shoes and shorts, took his yellow newspaper bag and set off on his newspaper round with his dog at about 5.45 am. He ran much of the route, as he usually did, and he took an interest in how long he took. He arrived home at about 6.42 — 6.43 am, entered by the front door, noticed that his mother's light was on and went to his own room. There he took off the paper bag and hung it up. He took off his shoes, took off his walkman and put it on the bed. He then went downstairs and into the bathroom. There he washed his hands to get off the black newsprint, sorted out some coloured clothes and jerseys (including a red sweatshirt he had worn on his paper run for the past week) and started the machine. He then went upstairs to his room, put on the light and noticed bullets and the trigger lock on the floor. He went to his mother's room, and found her dead. He visited the other rooms, heard Laniet gurgling and found his father dead in the lounge. He was devastated, and rang the emergency services in a state of acute distress. His case inevitably involved the proposition that Robin, having killed the other family members, had switched on the computer, typed in the message and committed suicide.
8. It has never been suggested that anyone other than either Robin or David was responsible for these killings or that the culprit, whoever it was, was not responsible for all of them. Thus, leaving the burden of proof aside, the question has always been, as the judge put it in the opening line of his summing-up, "Who did it? David Bain? Robin Bain?".
9. The trial before Williamson J and the jury lasted from 8-29 May 1995. During the trial over 60 witnesses were called to give oral evidence, some of them the same witnesses giving evidence on different aspects of the case, and over 20 written statements were read by consent. It will be appreciated that both the Crown case and the defence case were very much more complex than the simplified summary given above might suggest.
10. During the trial the judge was called upon to give a number of rulings. Two of these are relevant for present purposes. Both relate to evidence which the defence wished to call from a witness named Dean Cottle. Laniet had a cellphone registered in the name of Mr Cottle, and this led the police to interview him on 23 June 1994, three days after the killings. He made a statement, saying he had met Laniet about ten months earlier in a Dunedin bar, and they had become friends. According to Mr Cottle, Laniet had told him that she had been a prostitute and that her father Robin had been having sex with her for about a year and was still doing so. This was one of her reasons for leaving home. Later she said she was going to make a fresh start, her parents had been questioning her and she was going to tell them everything. In an affidavit dated 26 June 1995 (after the trial), Mr Cottle stated that on Friday 17 June, just before the killings, Laniet had said to him that she was going home that weekend to tell the family about everything that had been occurring, she was going to put a stop to everything, she was sick of "everyone getting up her". The incestuous relationship with her father had, she said, begun when the family were in Papua New Guinea.
11. The judge's first ruling was given on 24 May. In the course of his reasons the judge acknowledged that Mr Cottle's evidence was hearsay, but he did not rule out admission of the evidence on that ground:
"The present crimes were horrific and the jury, like every other person, will be considering why they occurred. Any evidence that might shed light on this must, in my view, be relevant. A motive for Robin Bain is certainly relevant to the primary issue in the case. If sufficient relevance were the only test then I would be inclined to admit the evidence despite its remoteness in time and questionable probative value."
But the judge regarded the reliability of the evidence as the real stumbling block. He was unable to conclude that it would be reasonably safe to admit the evidence or to conclude that the evidence would have sufficient reliability or probative value. He had already recorded that Mr Cottle, although subpoenaed to appear as a witness, had endeavoured to avoid service, had not appeared and could not be located.
12. The second ruling was given on 26 May, after prosecuting counsel had completed his closing address to the jury, when Mr Cottle voluntarily attended at the court office in answer to a warrant of arrest. On this occasion Mr Cottle was questioned in court about his failure to appear and his recollection of what Laniet had said to him. He was in a state of some confusion. The judge concluded that his evidence would not be reasonably safe or reliable, and said he did not believe him. He therefore again ruled against admission of this evidence, not because it was hearsay but because it was unreliable. Thus the jury never learned of this possible motive attributed to Robin.
13. In his summing-up the judge listed the points particularly relied on by the defence and then, drawing on the closing address of prosecuting counsel, the cardinal points relied on by the Crown. There were 12 such points:
(1) The rifle and ammunition were David's and the key to the trigger lock was in an unusual place where he had hidden it.
(2) David's bloodied fingerprints were found on the murder weapon.
(3) David's bloodstained gloves were found in Stephen's room.
(4) David had fresh injuries to his forehead and knee. There was no explanation for them and the nature of them indicated that it was he who had had the fight with Stephen.
(5) The glasses (with a missing lens) and fitting David's general glass prescription were found on a chair near where he was in his room when the police arrived, and, significantly, the left side of the frame was damaged and the missing lens was found in Stephen's room quite near his body.
(6) Blood-stained clothing, including a green jersey with fibres matching those found under Stephen's finger nails, was washed by David; and his Gondoliers sweatshirt with blood on the shoulder had been sponged.
(7) Blood found on the top of the washing machine powder container, porcelain basin and various light switches must have come from David's touch.
(8) Droplets of blood were found on David's socks as well as blood which had caused the luminol observed part sock prints in other parts of the house.
(9) The computer had been switched on at 6.44 am, and the jury would conclude on all the evidence that this was just after David had returned home from the paper run, if the evidence (including his own) were accepted that he was at the nearby corner at 6.40 am and that it would take 2-3 minutes to reach 65 Every Street.
(10) David's partial recovery of memory might have enabled him to suggest explanations for some of the blood on him but it did not explain other vital items such as the fingerprints, the clothes or the glasses. The Crown said that David confidently denied matters that he could not remember although they had happened.
(11) If David heard Laniet make gurgling noises, then she must then have been alive and consequently he had been by her bed when the last shot was fired. Other comments of his such as that his mother's eyes were open when he went in and his remark, to his aunt, that they were "dying, dying everywhere" tended to confirm that he remembered, in part, being there before the deaths.
(12) Not only did the expert pathologist say it was unlikely that Robin shot himself because of the angle of the gunshot wound, but Robin could not have killed the others because
(a) no one else's blood was found on him;
(b) there was no blood at all of any type on his socks or shoes;
(c) his fingerprints were not on the rifle, although if he had shot himself he would have been the last person to have gripped it firmly;
(d) no gun powder traces were found on his hands; and
(e) if he had been the wearer of blood-stained clothing and was intent on suicide, why would he have bothered to change his clothes and be in completely blood-free clothes when he shot himself?
14. Later in his summing-up the judge gave a standard direction on the proper approach to expert evidence, drawing attention to the evidence of Mr Jones (the senior police fingerprint technician) about the bloodied fingerprints on the rifle, and Dr Dempster who, the judge said, "may have impressed you as a very competent and experienced forensic pathologist". The judge reminded the jury of prosecuting counsel's suggestion that the Crown case had three angles: a mass of evidence implicating David; strong evidence excluding Robin as the killer of his wife and children; and overwhelming evidence establishing that Robin did not commit suicide. He reminded the jury that prosecuting counsel
"went on and said to you that although the evidence about the luminol sock foot prints in the house was tested at great length, there now can be no doubt that the prints were made by the Accused and so much of the evidence that you heard does not matter any longer in the sense that you need not worry about it; that, indeed, it need not have been called, since all the Accused now says, supports the evidence that those foot prints were his and that he went into those rooms and got wet blood on his socks."
The judge reminded the jury of prosecuting counsel's description of David as "increasingly disturbed", and of David's behaviour as "unusual and almost obsessional about some strange matters". This was indeed an accurate reflection of counsel's closing address, in which he had described David as "unusual in his behaviour" and a "disturbed young man". His behaviour had been described, more than once, as "bizarre". The judge referred again to the Crown submission about the glasses and the falling out of the lens, the switching on of the computer at 6.44 am after David's return home at 6.42—6.43, the absence of "one piece of evidence that Robin Bain had been into the rooms of the deceased on this particular morning", and the absence of any real evidence of suicide. In summarising the defence case, the judge referred to the statement of Mrs Laney, which had been read. This was evidence relevant to the time of David's return home from his newspaper round and had, the judge said, "assumed a particular significance". The judge referred to the acceptance by defence counsel that the luminol blood prints must have been David's.
15. The jury retired at 11.45 am on 29 May. At 5.23 pm they returned with four questions, which the judge duly discussed with counsel. The first question was: "The glasses found in David's/Stephen's rooms. Whose were they according to the optometrist?" The optometrist was Mr Sanderson, a witness who had given evidence. The judge reminded the jury of Mr Sanderson's evidence and also David's.
16. The second question related to a matter on which there was no evidence. The third question was a request to read Mrs Laney's evidence, bearing on the time of David's return home. The judge re-read her statement and that of another witness which the judge had not re-read in his summing-up.
17. The fourth question was a request to re-play the tape of David's telephone call to the emergency services. The tape was re-played.
18. The jury retired again at 5.42 pm. They returned at 9.10 pm and convicted on all five counts.
The first appeal
19. The appellant appealed to the Court of Appeal (Cooke P, Gault and Thomas JJ, "the first Court of Appeal") which, in a reserved judgment delivered by Thomas J, dismissed the appeal on 19 December 1995:  1 NZLR 129.
20. The principal question on appeal was whether the trial judge had erred in refusing to admit the evidence of Mr Cottle. But before addressing that issue the court observed that the Crown case appeared very strong and the defence theory not at all plausible. The jury obviously disbelieved David, as it was entitled to do. The court was satisfied that there had been no miscarriage of justice in the jury's verdicts. On the evidential issue, the court was unclear why the judge had refused to allow Mr Cottle to be questioned as to the truth of his statement, as counsel agreed that he had. But it held that the judge had been right to exclude the evidence, which it described as "clearly inadmissible". Certain secondary grounds of appeal were advanced, but it was accepted that none of these was sufficient in itself to justify setting the verdicts aside and the court, having considered the evidence closely, concluded that these grounds were totally lacking in merit. A petition for leave to appeal to this Board, primarily based on the evidential ground, was dismissed on 29 April 1996.
The second Court of Appeal
21. Following wide publicity, expressions of public concern and a joint review of the case by the New Zealand Police and the Police Complaints Authority, the appellant applied to the Governor-General for the exercise of the mercy of the Crown. On such an application the Governor-General in Council may, if he thinks fit, and if he desires the assistance of the Court of Appeal on any point arising in the case with a view to the determination of the application, refer that point to the Court of Appeal for its opinion thereon. The Court of Appeal must then consider the point so referred and furnish the Governor-General with its opinion thereon accordingly. That is the effect of section 406(b) of the Crimes Act 1961.
22. The Governor-General exercised his power under section 406(b). By an Order in Council made on 18 December 2000 he referred six questions to the Court of Appeal, specifying in relation to the first four questions a number of documents which the Court of Appeal was asked to consider. In the event the Court of Appeal (Keith, Tipping and Anderson JJ, "the second Court of Appeal") received over 50 affidavits from 42 deponents, 13 of those deponents being orally questioned before the court at a hearing which lasted from 14 to 18 October 2002.
23. The first of the six questions referred was:
"Was the computer turned on at a time earlier than 6.44 am on 20 June 1994 or, at the very least, is there a reasonable possibility that the computer could have been turned on at a time earlier than 6.44 am on that date?"
Reference was made to a number of sources of evidence, including one witness examined orally before the court. The Crown accepted (paragraph 14 of the judgment) that, if this question were answered literally, the evidence demonstrated at least the reasonable possibility that the computer had been turned on earlier than 6.44 am. Had the full evidence been before the jury at the trial (paragraph 15) they would have had to contemplate a switch-on time of 6.42 am, but the court could not say that was the correct time and it was not possible to say whether the actual switch-on time was earlier than 6.44 am. The court's answer to the first question (paragraph 16) was that
"there is definitely a reasonable possibility that the turn on time could have been earlier than 6.44 am on 20 June 1994."
24. The second of the questions referred was:
"Did the lens that was found in Stephen Bain's bedroom get there at a time or in a way that was unrelated to the murders or, at the very least, is there a reasonable possibility that this could have been so?"
Reference was made to four written documentary sources, the authors of three being examined before the court. Having considered all the manifold matters debated in relation to this matter, the court found it impossible to reach a firm conclusion. It considered that the possibility of the lens having got to where it was found, by a method other than planting, but still unrelated to the murders, was remote but could not be dismissed as fanciful. Its answer (paragraph 20) was:
"We consider the possibility of the presence of the lens being unrelated to the murders cannot be excluded or confirmed as a reasonable possibility without an examination of the whole case in the depth that a full appeal would involve."
25. The third question referred was:
"Were the applicant's positive fingerprint marks, made in blood, that were found on the rifle used to commit the murders, put there at some time before the murders or, at the very least, is there a reasonable possibility this could have been so?"
Reference was made to six documentary sources, three of the authors being examined before the court. The court said, in paragraph 22 of the judgment:
"The key question is whether the blood in which David Bain's fingerprint marks were found on the rifle was human blood. There was no suggestion at the trial that the blood was not human. Hence the jury will undoubtedly have proceeded on the basis that it was."
As a result of subsequent inquiries, tests and analyses there was now a suggestion that it was not human but animal blood. David was known to have used the gun some months earlier for shooting rabbits and possums. The court's answer (paragraph 22) was:
"From the scientific point of view, we consider it has been shown to be a reasonable possibility that the blood which bore David Bain's fingerprint marks could have been other than human blood. That being so, we consider it follows that there is a reasonable possibility that the marks could have been put on the rifle sometime before the murders."
26. The fourth question referred was:
"Was the submission made by the Crown Solicitor in the Crown's closing address to the jury at the applicant's trial that 'Only one person could have heard Laniet gurgling. That person is the murderer' wrong or misleading?"
Reference was made to five documentary sources. None of those witnesses was examined orally, although the court heard the oral evidence of Professor Ferris, a pathologist called by the Crown. Its conclusion (paragraph 25) was:
"The Crown Solicitor was in effect telling the jury, understandably as the evidence then stood (albeit the precise point was not addressed in evidence) that dead bodies cannot make gurgling noises. In the light of the evidence before us, we consider there is a reasonable possibility that this submission was wrong or misleading. Our opinion is therefore that the absoluteness of the Crown Solicitor's submission was wrong or misleading."
27. The fifth of the referred questions was:
"Does the Court of Appeal's opinion on questions 1, 2, 3 and 4 (whether taken individually or collectively) indicate that there is credible and cogent evidence available that might, if it had been placed before the jury, along with the other evidence given at the applicant's trial, have reasonably led the jury to return a different verdict?"
The court gave its answer in paragraph 26:
" There is credible and cogent evidence which suggests at least the reasonable possibility that the computer could have been switched on earlier than 6.44 am. There is credible and cogent evidence which suggests at least as a reasonable possibility that David Bain's fingerprints on the rifle could have been put there before the murders. There is credible and cogent evidence which suggests, as a reasonable possibility, that gurgling sounds can be emitted spontaneously from dead bodies. The absoluteness of the Crown's closing submission was, in this respect, wrong or misleading. When all this evidence is viewed collectively, we are of the opinion that it might, along with the other evidence given at David Bain's trial, have reasonably led the jury to return a different verdict. While the other evidence called by the Crown at the trial itself constituted credible and cogent evidence from which David Bain's guilt could be inferred, we consider that if the fresh evidence relevant to questions 1, 3 and 4 had been before the jury, it could reasonably have resulted in a different verdict. For these reasons we answer question 5 yes. Our answer does not imply that had the jury been presented with the further evidence it would necessarily, or even probably, have reached different verdicts. What we are saying is that in our opinion on the material before us, necessarily limited as it was, there is a reasonable possibility the jury may have done so."