The discussion about who was responsible was on the night of June 21 at the home of Bain's aunt and uncle, where the then 22-year-old was staying, Detective Sergeant Greg Dunne told the High Court at Christchurch yesterday.
Bain was "visibly upset, crying, sobbing and told me he couldn't help it", the witness said. "He told me black hands were coming to get them and he was not able to stop them; that if he'd run home, he may have saved them.
"He said hands were pulling them away and he wanted to blame someone."
At that stage, he and Bain discussed three options of who was responsible. They both discounted someone not connected to the family having entered the house and shot the family. Then they considered the other options, whether it was Bain or his father.
Bain said, "If it was Dad, I would be very disappointed," Det Sgt Dunne told the court, and he agreed with Crown counsel Cameron Mander that response from Bain was "most unusual".
Det Sgt Dunne was giving evidence on the seventh day of 36-year-old David Cullen Bain's retrial for the murders of Robin, Margaret, Arawa, Laniet and Stephen Bain at their Every St home on June 20, 1994.
The trial, before Justice Graham Panckhurst and a jury of seven women and five men, is expected to take about 12 weeks.
Bain is represented by Michael Reed QC, Helen Cull QC, Paul Morten and Matthew Karam, while Kieran Raftery, Mr Mander and Robin Bates are prosecuting.
During several interviews on the day of the shootings and the next day, Det Sgt Dunne said he asked Bain several times how he knew his whole family had been killed if he had not been into any of the other rooms. When Bain called 111, he asked for help, saying, "they're all dead".
Bain told him he did not know how he knew, as all he had seen was his mother, dead in her bed with blood all over her face and head, and his father, also with blood on his head, lying on the floor in the front lounge. He had not gone into the other bedrooms, had seen nothing else, Bain said.
He told the officer he returned home from his paper round, hung up his paper bag, took off his shoes and Walkman and went downstairs. He put on a load of washing, including the red top he had worn on his paper run, washed the newsprint ink from his hands, then went back up the stairs.
Bain said he had noticed the light on in his mother's bedroom and looked in. That was when he saw her lying dead and he told Det Sgt Dunne he then ran to the lounge, calling to his father. The young man also told him he did not want to open the door when the police arrived because "what I had seen scared me too much. I didn't want to see it again," Det Sgt Dunne told the court.
Asked who had been home the previous night, Bain said all six members of the family stayed at Every St on the Sunday night, which was unusual.
His father, who was the principal of Taieri Beach School, lived at the schoolhouse during the week although he was home at the weekends and also spent Monday nights at home when he had choir. He slept in a caravan on the Every St property.
Arawa lived at home, as did he and Stephen, with their mother, Margaret "and the animals", Bain said.
Laniet had been living in a flat, although she stayed with her father at Taieri Beach and he believed one of her friends had also gone to live in the schoolhouse. She was at Every St on the Sunday night because she had work in town on the Monday.
Arawa had gone out to do some babysitting and he did not know what time she came home as he was in bed. He had gone to bed about 8.50 and read a book until about 9.30. His parents and Laniet were still up, in the living room, and Stephen would have been going to bed.
Bain said he heard no sounds of arguing during the night, although he did hear someone driving away in the family car about 11pm, returning about 10 minutes later.
He was woken by his alarm about 5.30am, dozed for few minutes, as usual, then got up and left the house about 5.45am to do his paper run. He was wearing a new pair of running shoes, had his Walkman on and took the dog, Casey, with him, as usual.
There were no lights on when he got up and nobody else was up, he told Det Sgt Dunne. Asked if he had locked the front door behind him, Bain said the place was "very unlockable; you can't lock our house".
Det Sgt Dunne said he also asked Bain whether his parents had split up and Bain said they had not, but that his mother had got his father to sleep in the caravan. He spoke of the tension between his parents, of how things "went downhill" about a year after the family returned from Papua New Guinea, and he said his parents were always terse with each other.
His mother felt oppressed by his father, Bain told the witness. She had been partway through a music degree when she married Robin Bain and they went to Papua New Guinea when he (David) was 1 years old.
By the time his mother had Laniet, the second-youngest of the four children, she felt her life was for her husband's gratification, that he wanted her "in the kitchen", Bain said.
And when he was asked by Det Sgt Dunne what had happened at home on the Sunday night, Bain told him there had been an argument over a chainsaw. He wanted to use it on the section, but his father wanted to take it back to Taieri Beach.
He and his father had had constant battles "pushing and pulling over the chainsaw". His father was always "asserting his authority, his right to rule the roost. He's always like that."
Det Sgt Dunne said Bain told him that when he came back upstairs from putting the wash on, he noticed his bedroom was different from when he left the house. He saw cartridge shells on the floor, and the door of the cupboard where the rifle was kept was open.
The rifle had a lock and there were two keys, one of which he usually wore on a string around his neck, but which he had neglected to put on that morning. There was a spare in a pottery container on the desk. No-one else knew about that key, although they may have known about the one he usually wore around his neck. The spare key had been used, he said.
All his family knew about the rifle, which he last used several months earlier. His father was very familiar with firearms and had come with him to sight the rifle when he first got it.
The rifle was not still in the cupboard when he looked, and he did not know whether two magazines for the rifle were still in a plastic bread bag behind some shoes in the same cupboard. He had not looked as he "got a bit too hysterical", Bain told the witness.
He said "All I remember is calling 111, dragging the 'phone into my bedroom," Det Sgt Dunne said.
When asked about the family computer, Bain told him they all used it, but everything was open, and that he was "not a computer buff".
