Robin Bain killed his family because his incestuous relationship with daughter Laniet was about to be revealed, the defence in the David Bain murder trial told the High Court at Christchurch today.

Michael Reed QC, defending David Bain, introduced his team as the people who have "taken on the might" of the police and Crown.

He told the court that the defence case is that David Bain did not kill anyone.

"The father tragically killed four of the family and then himself," Mr Reed said.

"We ask you to wait and please keep an open mind," he said.

David Bain pleaded not guilty to five charges of murder at the start of the trial this morning.

Mr Reed said the defence will call "startling evidence" that includes forensic evidence.

"There is plenty of evidence that Robin Bain did kill the family and committed suicide," Mr Reed said.

Mr Reed told the jury Bain's sister Laniet was "going around telling everybody" about being sexually molested by Robin Bain.

He said Laniet was coming home to tell her mother of the sexual molestation.

Mr Reed said that was the trigger because Robin Bain, a missionary and school teacher, would have had his life ruined by the allegations.

He said Robin Bain had been living in a van for three years out the back of the school and when he came home in the weekend he was "bannished" to a campervan out the back of the house.

He said Laniet had stayed with Robin Bain in the van.

Mr Reed said the police arrested Bain soon after the murders and were then on a one-track cause.

He said that caused police not to investigate other leads.

Mr Reed said some of the evidence was lost, destroyed or never collected, including blood samples removed from Robin Bain's hands and under his finger nails.

"Laniet's diaries and letters written to her mother have been destroyed," Mr Reed said.

He said there could be allegations of the sexual molestation in those diaries but they have since been destroyed.

The computer with the "sorry" message is now also now broken after being returned to the family and left under a house.

He said the police have also "cherry picked" evidence that suits their case while ignoring other evidence.

Mr Reed said police knew from a neighbour about the allegations of incest but did not follow it up.

"We know Laniet was going home that night to tell all," Mr Reed said.

The prosecution

Earlier, Crown prosecutor Robin Bates graphically detailed the scene inside the Bain household in which five family members were found dead.

Mr Bates told the court how each of the bodies inside the house were found.

He said in Stephen Bain's room, it was clear that a "significant struggle had taken place".

Mr Bates said the room was in disarray and there was a large amount of blood.

He said Stephen had been shot twice with one bullet going through his hand and into his skull. The second shot killed him.

"Stephen appeared to have been strangled by the t-shirt he was wearing, it was bunched up around his neck," Mr Bates said.

He said Laniet Bain, David Bain's sister, had been shot three times.

His other sister, Arawa Bain, was shot once in the head after she left her bed.

Margaret Bain, the mother of David Bain, was found in her bedroom and died as a result of one shot to her head.

The father, Robin Bain, was found in the lounge, on his side, between a bean bag and a coffee table and had one bullet wound.

A .22 calibre rifle was found next to his body.

He said it is the Crown's case that David Bain killed his family members and it was not a murder-suicide by Robin Bain.

He said a computer with the message "Sorry, you are the only one who deserved to stay" was also found in the house and was an attempt to form an alibi.

The Crown's evidence against Bain

The Crown said they have evidence that shows Stephen Bain's blood was found on David Bain's clothing.

Mr Bates said a lense from Bain's glasses was found in Stephen's room while the frames and another lense were found in Bain's room.

He said this was part of the evidence that links Bain to the struggle which took place in his younger brother's room.

Mr Bates said the trigger lock and the key to the .22 calibre rifle were also found in David Bain's room.

He said Bain had also tried to wash blood out of some of his clothing, including a green jersey, in the laundry.

"Woollen green fibres were taken from under Stephen's finger nails which match the fibres from the green jersey," he said.

Mr Bates said a partial palm print of David Bain was found on the washing machine.

He said Bain was also seen to have scratches on his chest above his nipples.

Mr Bates said a policeman also noticed a bruise on Bain's temple, about the size of a 50 cent piece.

Mr Bates said no finger-prints belonging to Robin Bain were found on the .22 calibre rifle.

He said the computer screen with the message and the paper round are both potential alibis but the Crown has evidence regarding both of them.

Mr Bates said the turn-on times of the computer does not eliminate the possibility that Bain was the author of the computer message.

He said some witnesses have said that the paper round was done faster than usual.

Mr Bates said there was about 20 minutes of "lost time" between the time that the Crown believes he finished his paper round - 6.45am - and the 111 call made by Bain - 7.10am - from the family home.

"When asked about this [at the time], he said he had been going into trances or spacing out recently," he said.

Mr Bates said Bain had also displayed some "unusual behaviour" in the days leading up to the murders.

Mr Bates said Bain told a friend that he had had a premonition and that he "sometimes knew what was going to happen". He also "told her he had a feeling something horrible was going to happen".

Mr Bates told the jury that Robin Bain did not commit suicide but was murdered, along with his family on the morning of June 20, 1994.

He said Robin Bain was found dead in the lounge, near where the .22 calibre rifle was found, along with a 10 shot magazine.

Robin Bain had a full bladder when he died.

Mr Bates said that meant it was unlikely he was involved in the struggle with Stephen Bain and was going about his normal routine which included collecting the morning paper.

Mr Bates said there were no fresh injuries on Robin Bain's body, only older injuries on his hands.

Mr Bates said while there was blood on Robin Bain's clothes, none of it links him to the murders.

He also gave a short description of some of the things David Bain said to police following the alleged murder of his parents, two sisters and brother.

Mr Bates said Bain could not explain how he had received the bruise to his head and other injuries found by a doctor in the days following the murders.

All of the family had used the computer where the "sorry" message was found.

Mr Bates said Bain did not remember telling anyone he had had a premonition of the murders.

He said Bain also said he did not recall wearing the glasses, one lense of which was found in Stephen Bain's room, the other lense was found in Bain's room.

Judge addresses jury

Earlier Justice Panckhurst told the jury they must put any "baggage" to one side and approach the case with an open mind.

Bain was read the five charges by the registrar and answered not guilty to each one in a steady voice with his hands by his side.

Bain is being retried in the High Court at Christchurch for the murder of his parents and three siblings in Dunedin in June 1994 - killings that rocked New Zealand at the time, and have continued to fascinate.

The judge told the jury: "I appreciate that having been selected to serve on this jury is a significant moment.

"What is required of you is to make an entirely fresh start."

He said a lot has been written on the case, including books, but jurors must not seek out information from other sources.

"All that you've read, heard or seen is to be discarded," Justice Panckhurst said.

He said the onus to prove the murder charge rests with the Crown, which must prove it beyond reasonable doubt.

Arthur Allan Thomas, who was wrongly convicted for the 1970s killings of a Waikato farming couple, was at court today to support Bain.

Smiled

Bain, who smiled at media but made no comment as he arrived at court earlier, stood throughout the jury selection process.

The 12 members of the jury were selected from a pool of 80 potential jurors in a crowded court room with defence lawyers using three of their allowed challenges to possible jury members and the prosecution using two of theirs.

Justice Panckhurst said he had no doubt that potential jurors were aware of the case but if they had any personal connections to people who served as police officers in Dunedin in 1994, ESR scientists, St John ambulance officers or the Cullen and Bain families, then they should approach the bench.

Justice Pankhurst said there would be 150 Crown witnesses called during the trial.

Four potential jurors did approach the bench and three were excused - two because they had a potential connection to witnesses and one for medical reasons.