Two crucial minutes were the focus of attention at the David Bain murder retrial in the High Court at Christchurch today.
A computer specialist tracking when a farewell message was left on the Bain family computer could determine only how long the computer had been on.
The message "sorry you are the only one who deserved to stay" was likely to have been left by the killer. When Martin Cox tried to pinpoint the precise time the computer was switched on, he had to rely on the watch of a police officer, which later proved to be two minutes out.
The precise time it was written was important, as it could be compared with the time David Bain arrived home from his paper round.
Bain is accused of the murder of his parents and three siblings in their Dunedin home in 1994. He is alleged to have shot dead has his father Robin, mother Margaret, sisters Arawa and Laniet, and brother Stephen.
The defence argues his father Robin Bain carried out the killings, then committed suicide.
Mr Cox, a software engineer from Otago University, told today's hearing he had worked out when the computer was started on the morning of the killings in June 1994.
He could not work out exactly when the message had been typed, as the time and date had never been set on the computer.
He compared the time that he saved the message with the time the computer thought it was, to calculate the machine had been turned on 31 hours 32 minutes earlier.
When he had finished, he asked that the watch worn by Detective Kevin Anderson, who recorded the times arrived at by Mr Cox, be checked.
Police did not do this until nine days later, then did not tell Mr Cox the watch was two minutes out.
By the time Mr Cox found out there was a two-minute difference, he had given his evidence at the depositions stage and the trial of Bain.
Bain's lawyer Michael Reed QC said the jury in the first trial in 1995 were given a computer turn-on time of 6.44am, when the true time was more likely to be 6.42am.
Mr Reed asked Mr Cox if he had been asked to sign a sworn document that his timings were correct, without being told of the error.
Mr Cox agreed he had.
Earlier, Mr Anderson showed the jury the blood spattered curtain taken from between the alcove and the lounge where Robin Bain was found.
He described the scene search of Bain's bedroom, saying a large amount of ammunition was found in the bottom of his wardrobe. A large cardboard target was also found in the room.
The target was in court yesterday. It had five large red circles on it and holes through it.
The trial is before Justice Graham Panckhurst and a jury.
