After a three-month retrial, the David Bain jury had to consider whether there was reasonable doubt over eight crucial areas of evidence.
Either the Crown has proved that David committed the five murders or there is reasonable doubt and the five counts result in acquittal," Justice Graham Panckhurst told the Bain jury.
And so, after a murder retrial lasting more than three months, which heard evidence from 184 witnesses, reviewed statements, graphics, photographs, film and an audio of David Bain's 111 call on the morning of 20 June 1994, the case boiled down to a fundamental question: Did David kill five members of his family, or did his father Robin shoot them before turning the gun on himself, as the defence argued through the long days of testimony.
The judge put it this way: Was it proven beyond reasonable doubt that David killed his family, which meant the Crown had proven, beyond reasonable doubt, that it was not a case of suicide?
Yesterday, after deliberating for less than a day, the five men and seven women jurors answered Justice Panckhurst's question: Not guilty, on each of the counts. David Bain, who had spent more than 12 years behind bars, was a free man.
The verdicts reversed the findings a Dunedin jury reached on the same murder charges in May 1995. Yesterday morning, the jury asked Justice Panckhurst the meaning of "reasonable doubt". He replied that there were no rules as such, but reasonable doubt meant the jury had to be sure David was the killer.
A reasonable doubt was an honest and reasonable uncertainty. If they were not sure, they had to acquit the accused, the judge said. Earlier he had told them they had to be unanimous. Twelve-nil, he said.
Locked away to consider their verdict the jury would have focused on eight crucial areas of evidence, areas where expert witnesses often provided conflicting opinions but where the Crown and the defence spent much of their efforts since Bain's second murder trial began on March 6. The lawyers argued for weeks. The jury took only five hours and 50 minutes to reach unanimous verdicts. These are the critical areas where the jury found there was reasonable doubt:
It's a humble lens from a pair of glasses, but it turned out to be a big issue for the jury to consider in the Bain retrial. The lens was found, according to police, in the bedroom of David's younger brother, Stephen, 14, three days after the killings during a search of the family home.
It was found to fit a pair of spectacle frames that were on a chair in David's bedroom. Another lens fitting the glasses was also found in Bain's room.
The glasses were first thought to belong to David, then were found to be an old pair of his mother's glasses that the prosecution said David had used while his own were being repaired.
The prosecution said the lens fell from the glasses, worn by David, when he got into a violent struggle with his younger brother Stephen on the morning of the murders. Stephen struggled with his killer before being shot in the top of the head.
The defence said David had not worn these glasses, and accused the policeman in charge of the Bain house "crime scene", Detective Sergeant Milton Weir, of planting the lens in Stephen's bedroom.
David could not explain why the frames and a lens were in his room.
Bain's lawyer, Michael Reed, QC, went on the attack when Mr Weir took the stand in the trial, pointing to a photograph of the clutter on Stephen's bedroom floor where he suggested a gap had been created.
Mr Reed: "I put to you, Mr Weir, that you put your hand in there and put that lens in there."
Mr Weir: "There is no way that I planted the lens in that room."
Two police officers who examined Stephen's room alongside Mr Weir took the stand in the trial, and both said they never saw Mr Weir plant anything, but were not always with him.
One of these officers, Detective Jacques Legros, said: "I can't exclude it 100 per cent. But I have worked with ... Milton Weir for a period of time and I don't believe he would have stooped that low."
The question of whether the lens fell to the floor or was planted became more complex with a dispute about exactly where the lens was in the bedroom.
Mr Weir initially said he found the lens under an ice skating boot under clothing on the floor of Stephen's room. Later, when he viewed photographs taken in the bedroom, he observed what he thought was the lens in front of the toe of the skating boot.
His evidence to the jury in David's 1995 trial reflected this observation. However, Mr Weir said he later learned what he thought was the lens in the photograph was an trick of light called a "specular effect".
Mr Reed put it to him that, as a result, he had misled the jury in the first murder trial.
Mr Weir: "Not intentionally. No, I did not."
Mr Reed maintained it could not have been an innocent mistake when the "fake lens" would have been spotted earlier by others.
Mr Weir: "Well, I'm telling you that that's what happened, Mr Reed. It's like I have said before, if it had been a big red brick, you would have a point. But I'm talking about a small piece of glass."
The issue for the jury was complicated further with evidence from optometrist Gordon Sanderson, who was brought in to give specialist advice to police.
Mr Sanderson initially gave the view the glasses in David's room belonged to David, but later changed his opinion to say they belonged to David's mother, Margaret.
Because of the similarity in prescriptions between the two, David would have had 90 per cent vision when wearing his mother's glasses, but Robin would not have had any visual help from the glasses.
Mr Sanderson said he conveyed this change in his opinion to Mr Weir, but was shocked when it was not, in turn, conveyed in evidence to the jury in the 1995 trial.
Mr Weir told the court: "I have no recollection of having a conversation with Mr Sanderson where I was going to change his evidence."
Mr Sanderson said he also spoke with Mr Weir about the issue of dust on the lens found in Stephen's room, but this never came up in evidence either.
Dust could imply it had been there for longer than a few days. Mr Weir said this conversation never happened.
THE BLOODY SOCKPRINTS
Bloody sockprints left in the Bain house, probably by the killer, added another level of intrigue to the case.
The prints left by feet wearing bloodied socks were found in the hallway and the bedroom of Margaret Bain after the killings. The blood is likely to have come from the bedroom of David's brother Stephen, 14, where a bloody struggle took place.
Former Environmental Science and Research (ESR) forensic scientist Peter Hentschel, who assisted police in examining the crime scene, found the prints using the chemical luminol, which glows when reacting with blood.
Mr Hentschel measured the length of the only two complete right foot prints he found at 280mm long - and this measurement would become the basis for heated debate over who could have left them.
Prosecutor Kieran Raftery said Mr Hentschel measured the prints only from the toe "area" to the heel "area", and therefore the full print could have been larger.
Mr Hentschel said he found blood on the soles of the socks David was wearing on the day of the killings, but none of the soles of Robin's socks.
Therefore, Robin would have had to change his bloodied socks for clean ones after murdering his family and before committing suicide. The defence put this down to the workings of an irrational mind.
Mr Reed: "Did Robin, a religious man, want to meet his maker in a fearful state with blood over him? We don't know what was in that man's mind."
The prints were lost when the Bain house was burned to the ground.
Mr Hentschel said his view was that the prints were left by someone with feet bigger than the complete print length of 280mm.
David's foot was measured at 300mm, and Robin's at 270mm.
Mr Reed put it to Mr Hentschel that the foot that left the sockprints could not have been bigger than 280mm, and tests would show this.
Mr Hentschel: "If they show that, then I would be wrong."
ESR forensic scientist Kevan Walsh, for the prosecution, told the court how he performed tests with socks soaked in animal blood, placed on to card to take off the excess, and then on to carpet. He used his own feet, at 298mm long to mimic David and a volunteer with feet the size of Robin for his testing.
He measured the resulting prints after spraying them with luminol.
Mr Walsh said the testing of his own foot, to mimic David, got an average size sockprint walking on carpet of 297mm, and nothing smaller than 286mm. With testing of a foot the size of Robin's, Mr Walsh said the average size bloody sockprint was 282mm.
Mr Reed: "And the conclusion you have drawn from that is ... that a person with a 270mm foot, walking on carpet ... is most likely to leave a print of approximately 280mm?"
Mr Walsh: "Yes."
However, the prosecution said this was not a valid comparison to the prints in the house, and Justice Graham Panckhurst also raised doubts by pointing out that the bloodied socks had not been put straight on to carpet as had occurred in the Bain house.
Mr Reed: "So we have the extraordinary situation of the Crown attempting to discredit their own tests".
Forensic science consultant Anna Sandiford, for the defence, carried out the same experiments as Mr Walsh, using David himself.
David wore a sock soaked in cow's blood, and the prints he left on carpet were sprayed with luminol and measured.
Dr Sandiford said the luminol mark David left was on average 306mm long. The range of prints left was 300mm to 315mm, and never less than the actual foot length.
Dr Sandiford said that, based on the results of her tests, David Bain's right foot could not have made the prints recorded in the house.
Mr Reed: "Even on the Crown's own evidence, those bloodied sockprints were made by Robin. It's as obvious as night follows day."
The defence criticised the police for not cutting out the areas of carpet with the prints before the Bain house was destroyed by fire about two weeks after the killings.
THE RIFLE AND THE FINGERPRINTS
The prosecution put forward the presence of David Bain's fingerprints "in blood" on the murder weapon as a key plank of their case that David was the killer.
The jury was presented with a scenario from the prosecution that David put his bloodied fingers on the wooden stock of his Winchester semi-automatic .22 rifle and left the prints when he shot his brother Stephen in the head after a violent and bloody struggle.
The defence said it was not unusual for David's fingerprints to be on his own gun. They said these prints were left there several months before the killings when David went hunting, and were in sweat and maybe other contaminant like gun oil, but definitely not blood.
Robin's prints were not found on the rifle, but the defence said this was not unusual.
Mr Reed said statistics showed that in only about 3 per cents of homicides would you find the fingerprints of the person using the gun. He also pointed to about eight or nine other prints on the rifle, which could not be identified because of their state.
Bloodied gloves, which were worn by the killer, were found under Stephen's bed after the killings. David had bought these gloves for a ball he attended.
Prosecutor Kieran Raftery said David wore these gloves to prevent his prints getting on the rifle, but due to the unexpected struggle with Stephen, either took the bloodied gloves off, or had them pulled off him.
There was no reason for Robin to wear those gloves, Mr Raftery said.
"You wear gloves, members of the jury, if you don't want to leave fingerprints. That's why someone who's going to kill, and wants to get away with it, will wear gloves."
Mr Raftery emphasised David kept his rifle locked in his bedroom with the ammunition and ammunition magazines. There were only two keys to open the trigger lock securing the rifle - one David wore on a string around his neck, later found in David's anorak in his father's Commer van, and the second in a container on the desk in his room.
David made a "Freudian slip" when he told police only he knew where this second key was kept, Mr Raftery said.
But Mr Reed said it was no "State secret" where the key was kept.
Former ESR scientist Peter Hentschel said he took a sample of material in the area of the prints on the stock, which fellow scientist Peter Cropp then tested and found to be of human origin.
But the defence disputed where this sample came from, saying it was not actually from the prints themselves but nearby, and the presence of human DNA had never been proven under the prints.
The time at which David heard his sister Laniet gurgling was another key issue for the jury to consider.
David told police that he heard Laniet, 18, making the noise when he arrived home from his paper round on the morning of the killings. His defence team said Laniet could have still been in the process of dying or could have been already dead but still producing sounds.
The prosecution rejected this, saying David must have shot Laniet to hear this sound from her.
David initially told police he found only the bodies of his parents when he arrived home that morning, but months later made a statement that he had been able to recall going into the bedrooms of his three siblings as well.
In relation to Laniet, he stated: "When I went into the room I heard groaning-type sounds, muffled by what sounded like water. I turned on the light, it came from her. Went over to her. I could see there was nothing I could do. I didn't touch her."
Mr Raftery said in this situation the usual reaction would be to seek help.
"If you're genuinely home from the paper round, and you hear that sign of life, you would do what any human being would do. You would strain heaven and Earth to get someone there as fast as possible - 'my sister is still alive'.
"But no. He waits 15 minutes or 20 minutes before he telephones and tells the 111 caller ... 'they're all dead'."
Mr Reed said when David found his sister horribly injured, "he knew the situation".
The prosecution theory was that David had shot Laniet in the cheek before moving on to kill the rest of the family. When he returned to hear Laniet still making noises he would have finished her off with further shots to the head. Laniet was shot in the left cheek, above the left ear, and in the top of her head.
Pathologist Alexander Dempster, who did the autopsies on the Bain family, said the first shot Laniet suffered was likely through her cheek, and this was supported by other pathologists for the prosecution, Ken Thomson and Professor James Ferris.
The cheek shot could have left Laniet conscious enough to sit up and put her hand on her face to check what had happened, Dr Dempster said.
Gurgling sounds could have been heard as she inhaled fluids that obstructed her airway.
The second shot was likely above her ear before the final shot with the rifle silencer pressed against her head causing an "extraordinarily large" wound, Dr Dempster said.
He said he would be surprised if Laniet lived for any time after these wounds, but it was possible.
Dr Ferris said Laniet survived long enough to inhale blood into her lungs after the cheek shot and any attempts to inhale air through an airway containing blood could produce a gurgling noise.
But the two wounds Laniet suffered to the head would both have resulted in "virtual complete destruction of the central part of the brain responsible for breathing and keeping one alive".
Various experts for the defence gave a version of Laniet being shot first in the head and then the cheek.
Melbourne forensic scientist Peter Ross said his hypothesis was that Laniet had been shot first in the top of the head when sitting up as if to get out of bed.
She must have been shot again in quick succession in an upright position before slumping on the bed.
Forensic pathologist Robert Chapman, from Windsor, England, said it was possible there would be a period of survival for a period of minutes after Laniet was shot, and some respiration had occurred to allow her to produce the gurgling noise. Breathing through blood could produce a type of snoring noise.
Melbourne pathology professor Stephen Cordner agreed Laniet could have kept breathing for a period of minutes rather than hours after the shots.
Mr Ross said he had personally heard a groaning noise come from a woman about an hour after she was declared dead.
ROBIN AND THE INCEST MOTIVE
The jury was faced with two very different versions of Robin Bain to consider.
One was of a deeply depressed man who was having sex with his own daughter and feared this being made public. The other is of a loving father and pacifist who believed in the right of all things to live.
The defence said Robin snapped on the morning of June 20, 1994, and murdered his family, perhaps afraid of the consequences of his long-term sexual relationship with his daughter Laniet being exposed.
A series of witnesses, including Laniet's friends, fellow prostitutes, and an employer all told of Laniet opening up about her father having sex with her.
Witnesses also spoke of Laniet making various comments about being raped in Papua New Guinea by a family friend or her father, giving birth to her father's child, having black or white babies, and having an abortion. A friend and a fellow prostitute both spoke of seeing stretch marks on Laniet's stomach.
A shop owner, who cannot be named, said Laniet was a frequent customer in his store and one day in 1994 she came in crying and upset.
"I asked Laniet if she was all right, what was the matter. And Laniet expressed a lot of things about what was going on at home, the relationship with her mother, and that she was having an affair with her father.
"I was completely gobsmacked. I didn't know how to respond."
Defence witnesses spoke of Laniet going home the weekend before the killings to "blow the whistle" on what had been going on, and the defence said this could have prompted an already depressed Robin to kill.
Mr Reed: "We don't know what is the truth of what really was happening between Laniet and her father ... but we do know as a fact that Laniet was going around telling people [about incest]. Just imagine on that Sunday night if Laniet had blurted out at home ... and makes an allegation of incest.
"You have only got to make an allegation of sexual misconduct and your life is ruined."
But prosecution witnesses said David had actually called a family meeting that weekend, and that Laniet was afraid of going, but she would be dragged there "kicking and screaming" by David if she did not go.
The things Laniet were telling people were either exaggerations or deliberate lies, and the motive of trying to stop the incest being exposed did not add up.
Mr Raftery: "If this is a dark family secret, and [Robin is] in the depths of depression and he wants that secret to go, not just to his grave, but to the graves of all his family members, why does he leave one alive who could possibly reveal the dark secret?"
The only source of incest allegations was Laniet, Mr Raftery said.
Based on her various comments, Laniet, by the age of 12-and-a-half, would have had three babies to three different men, including a black child and two white children and an abortion.
"No one else said she was pregnant to anyone, and even David said it was nonsense. Laniet was not the most reliable source."
Laniet's doctor, Marjolein Copeland, told of an occasion in November 1993 where she told Laniet she should abstain from sex for four days because of a potential sexually transmitted disease.
Laniet stated she was going to be staying with her father over that time and "that's not going to be easy", before hastily leaving the surgery, Dr Copeland said.
Mr Raftery: "Laniet mentions it to a dairy owner when she's buying a packet of cigarettes and a packet of milk that she's committing incest with her father, you might think she would have shared that with her GP."
The prosecution pointed to the fact that Laniet, having left the family home and tired of flatting, went to live with her father at a house at Taieri Beach School, where her father was principal, in the weeks prior to the killing.
But Mr Reed said the fact that she organised for a boarder to came to stay at the school house as well showed she was looking for a way to prevent her father's advances.
Various friends and colleagues of Robin described him as warm, kind, gentle, a proud father and a devoted principal.
Darlene Thomson, a school colleague of Robin's, recalled a spider coming into a classroom and some of the children wanting to kill it. Robin became upset about this and instead taught the pupils about the spider and set it free, she said.
"The lesson was 'everything has a right to live'."
Dorothy Duthie was board of trustees chairwoman at the school, and recalled an incident where Robin Bain refused to dispose of a live possum in a trap.
"He certainly didn't want to do the shooting."
The defence said this evidence was at odds with the fact that Robin was himself a hunter, helped David sight in his rifle, and had used .22 ammunition in the caravan where he slept at the rear of the Bain family home.
Mr Reed said Robin had become depressed following the break-up of his marriage and repeatedly being turned down for jobs he applied for.
Defence witnesses described Robin in the months before his death as appearing unmotivated and gaunt. They said he had lost pride in his appearance and had poor hygiene.
Witnesses said Robin had sought stress leave or someone to relieve for him at the school around time of the murders.
Educational psychologist Cyril Wilden said Robin seemed to have deep-seated emotional problems. After the killings, Mr Wilden helped counsel Robin's pupils and found graphic and disturbing stories written by the pupils about murdering family members.
Robin, as principal, had allowed these stories to be sent out to the childrens' families.
Mr Wilden said he also spoke to two pupils alleging Robin had hit them.
SUICIDE OR HOMICIDE?
Whether Robin Bain committed suicide is perhaps the central issue the jury had to consider.
If Robin took his own life, then it would follow that he also shot dead his family. But the prosecution said it was unlikely or impossible Robin used the .22 rifle to shoot himself in the left temple, and this fatal shot had to be fired by David.
Experts were lined up on both sides of the argument, with much of the debate centred around the gunshot wound Robin suffered. How far the rifle was from the head when fired was crucial as to whether suicide was possible.
Features of a gunshot wound such as blackening and powder marks could give clues as to how far away the gun was when fired.
The bullet that struck Robin the temple travelled in a upward trajectory through his brain, resulting in his death.
Pathologist Alexander Dempster was the only one to physically examine Robin's body and he came to the view that Robin's wound was an "angled near contact wound", meaning the rifle silencer was on an angle and virtually against the head.
"My conclusion was that this was unlikely to be a self-inflicted gunshot wound, but I couldn't exclude that possibility completely," Dr Dempster said.
"I had never seen a self-inflicted wound which was even close to this trajectory."
However the defence put forward a range of scenarios showing how Robin could have held the rifle in order to inflict the fatal blow on himself, which Dr Dempster accepted were possibilities.
Ballistics expert Philip Boyce showed it could be done with the rifle butt against the floor or on a chair, and his own testing indicated that the trigger could be pulled with the rifle as far as 12cm away from the head.
He found Robin could have committed suicide with ease in these positions, and that it was more likely than not that Robin shot himself.
The prosecution said though these theories might be possible, they were unlikely. A person committing suicide would lose the line of vision to the trigger and have to fiddle around for it.
Why do it like this when there were easier ways, Mr Raftery said.
Three scientific experts called by the prosecution analysed photographs of Robin's wound and came to the conclusion that the rifle was a distance from the head of Robin when fired.
Environmental Science and Research (ESR) scientist Kevan Walsh said a range beyond 20cm, pathologist Ken Thomson said 16cm to 20cm, and pathology professor James Ferris said between 30cm and 42cm.
Asked about the possibility of suicide at the range he calculated, Professor Ferris said: "In my view it would be simply impossible to self-inflict the injury we see".
For the defence, British pathologist Dr Robert Chapman, famed for doing Princess Diana's autopsy, said Robin's wound was a "contact or near-contact" wound, with the rifle silencer against or virtually against the head.
Asked by about his opinion on whether it was likely to be suicide or not, Dr Chapman said: "I would say that that wound, based on the wound appearances and the pathology aspects ... is consistent with a self-inflicted injury".
Melbourne pathologist professor Stephen Cordner agreed it was a contact or near-contact wound and "perfectly compatible with self-infliction".
Statistics were thrown into the mix, with the prosecution seeking to show it would be rare for a right-handed person like Robin to opt to shoot himself in the left temple.
Prosecutor Cameron Mander put to Dr Cordner a published article reviewing 1704 cases of suicide using a rifle. It said 22.9 per cent were to the right temple and only 3.3 per cent to the left temple.
Dr Cordner did not agree that the left temple was an unlikely or less probable site for Robin to commit suicide.
British scientist John Manlove, for the defence, analysed blood staining on Robin's pants and focused on an unusual patterns of blood going in two different directions on the leg of Robin's pants.
Dr Manlove found a suicidal stance suggested by Mr Boyce, with Robin's leg raised onto a chair, explained the patterns, as blood would impact both above and below the bent knee.
The defence said this blood staining ruled out theories that Robin was standing or kneeling to pray when shot by David. The prosecution said Robin could have been sitting with his legs folded in front of him, but the defence said this would be an uncomfortable position for an adult man.
Mr Boyce said Robin could have fallen backwards to finish in the position where his body was on its side, partially against a bean bag.
But Dr Ferris said blood on the curtains in the lounge where Robin's body was found suggested the body was moved.
STEPHEN'S MURDER AND THE DNA
The prosecution pointed to the murder of Stephen as the strongest indicator of David's guilt.
Stephen fought back against his killer, which resulted in a violent struggle, leaving blood staining throughout his bedroom.
Pathologist Alexander Dempster said a .22 bullet was found in Stephen's pillow after apparently striking Stephen.
"My interpretation was that the bullet passed through the left hand and then grazed the head and then ended up in the pillow. I think that would have probably accounted for a lot of the blood present at the scene."
Stephen would have been able to continue to fight after this wound. However, it is likely he was then choked with his own T-shirt, leaving injuries to his neck, Dr Dempster said.
"He has been effectively strangled. I would have thought most probably to the point of being incapable of continuing the fight, and has then has been shot finally with a bullet though the top of the head."
Mr Raftery said the fingerprints left on the rifle by David were consistent with the rifle being pushed down to deliver the final fatal shot to the top of Stephen's head.
Blood was found on clothing David wore that day, including his socks, shorts and white shirt.
ESR forensic scientist Sally-Ann Harbison gave evidence of testing samples from blood on David's clothing for DNA.
She said she found DNA matches to Stephen in three samples on David's sock, from samples on the front left, upper back and lower back of David's white shirt, and in a sample taken from a bloodstain on the crotch of David's black shorts.
Stephen's DNA was also found on the rifle. Dr Harbison said blood samples taken from Robin were also tested and the only DNA matches were to Robin.
The prosecution said Stephen's blood and DNA must have got on David when they fought and David murdered his brother. David was also accusing of washing a bloodied jersey he wore in the killings.
David initially told police after the killings that he did not go into his siblings' bedrooms. But months later, after sessions with a psychologist, said he was able to remember going into those rooms and seeing their bodies.
In his evidence in his 1995 trial, David said he went into Stephen's bedroom and found him "covered in blood".
"He looked as if he had blusher all over his face and down his neck. I got down beside him and touched his shoulder to see if I could wake him, but he didn't move at all."
The defence said this explained the traces of blood from Stephen on his clothing.
It would be suspicious if there was no blood on him at all, Mr Reed said. Yet if David had been in a violent struggle, with blood "flying around", then there should have been a lot more blood than the "little bits" on David.
Mr Reed pointed to photographs showing blood spots on Robin's hands that were never tested. These possible clues to Robin's guilt went with him to the grave.
The one sample that was taken from Robin's hands was destroyed by police in 1996.
Using modern testing methods, this blood on Robin's hands could have been identified as belonging to Stephen, Mr Reed said.
"David doesn't have that privilege of proving himself innocent as he would like to."
Dental surgeon Donald Adams, for the defence, said a series of marks on Robin's knuckles could have been the result of his fist coming into contact with Stephen's teeth.
Stephen was described as feisty and able to defend himself, and the prosecution said Robin, 58 and frail, was not physically up to subduing Stephen.
But Mr Reed said Robin weighed 72kg and Stephen 55kg, and would find the necessary strength when the adrenaline was flowing through his body.
THE COMPUTER AND THE PAPER ROUND
The jury was asked to consider various key timings and whether they supported David or Robin as the killer. In particular, these timings related to the computer in the Bain house and David's daily paper round.
At issue is when the computer was turned on, and a message typed on it which read: "Sorry, you are the only one who deserved to stay".
Computer experts have attempted to estimate the time the computer was switched on, but Mr Raftery said the short answer was "we don't know".
All that was known was that it was some time between 6.40am and 6.45am.
The defence said the computer could have been turned on as early as 6.39am and the evidence showed David left for his paper round about 5.50am and arrived home as usual about 6.45am.
David could not have turned the computer on and written that message to frame Robin.
The prosecution said the alarm clock in the caravan where Robin was sleeping was set for 6.32am, and if this alarm had gone off and he got up at this time, it gave him only a short time to carry out the murders, type the message and commit suicide before David arrived home.
David could have shot four of his family, then completed his paper run earlier than normal so he could get home, shoot his father coming into the house from the caravan, and type the message.
David went out of his way to be noticed at certain points on the paper round to create an alibi, Mr Raftery said.
Kathleen Mitchell, now deceased, told police in a revised statement in 2007 that she heard David open the wrought iron gates on her property and come up on to her balcony the morning he delivered her newspaper.
"He had never done this before and there was no need for him to do this."
Mrs Mitchell said because David came through the gate, her dog Boris barked and she glimpsed David through the window.
"He said 'hello' and I said 'hello' back. The circumstances that morning were unusual and since that day I have often thought about it."
Policeman Malcolm Parker was also on David's delivery route and said he noticed his newspaper in the driveway just after 6.35am.
"It was unusual because I had never got the paper that early."
The defence relied on other witnesses who said they saw David that morning at locations they would normally expect him to be.
Witness Denise Laney said she saw David, whom she only knew as the paperboy, squeezing through the gate at his home as she drove past on her way to work.
She said she would usually see him further down the street, and was afraid she was late for work. She said she checked the digital clock in her car and it read 6.50am. The clock was found to be five minutes' fast.
The defence said this 6.45am return time ruled out David as the murderer.
Because the typed message was not saved on the computer, computer expert Martin Cox was brought in by police a day after the killings to try to work out when it was switched on.
He saved the message to the computer's hard disk. Though the internal computer clock was not set, the act of saving was like stopping a stopwatch and that gave a time difference of 31 hours and 32 minutes.
By counting back, Mr Cox determined the computer was switched on at 6.44am on the day of the murders.
He later had to revise this to 6.42am when he found out the watch he was working off when he saved the message, belonging to Detective Kevin Anderson, was two minutes' fast.
Closer computer analysis found the turn-on time would have to be adjusted to 6.41.06am.
What Mr Cox could not be sure of was how long it took him to carry out the the process of saving the message. This could further alter the estimated turn-on time.
While Mr Cox said it could be minutes, the defence said it might be only a matter of seconds.
The national manager of police's electronic Crime Laboratory, Maarten Kleintjes looked at all the possibilities and said theoretically it could have taken six minutes.
But defence computer expert Bryan Thomas rubbished this suggestion, saying it would take him between one and two minutes.
THE BAIN FAMILY
Born 25 November 1935
At the time of his death Robin Bain was a lonely and depressed man. A school headmaster, he was sleeping in a van on the family's property, estranged from his wife. Once considered a "gentle pacifist", Robin had gone from being chatty, positive and well-presented to losing all motivation and interest in life after being turned down for a series of jobs.
Margaret Arawa Bain(nee Cullen)
Born 11 October 1943
Margaret and Robin went to Papua New Guinea as missionaries for 15 years. On her return to Dunedin she became immersed in spiritual matters. A witness told the trial Margaret had "new age" ideas and believed she was related to famous people, including Winston Churchill.
Arawa Mary Bain
Born 26 June 1974
Nineteen when she was fatally shot, Arawa Bain was training to be a teacher. Intelligent and talented, she rose to become head girl at Bayfield High School.
Born 19 March 1976
Laniet had an unhappy few years prior to her death at 18. She had been using drugs, worked as a prostitute and, according to trial witnesses, had an incestuous relationship with her father Robin. She also told people she had been raped when the family lived in Papua New Guinea, and had given birth to a black child.
Stephen Robin Bain
Born 1 January 1980
Fourteen-year-old Stephen, the youngest Bain, was robust, tenacious and physical, a gangly youngster with big hands and feet. He played trumpet in the Bayfield High School band and was a keen cricketer. Awoken before dawn with a gun at his head, he fought tenaciously with his killer to live.
After a three-month retrial, the David Bain jury had to consider whether there was reasonable doubt over eight crucial areas of evidence.