A pathologist has told the High Court in Christchurch that by the time he was allowed into the Bain house 15 years ago, it was too late to test the core body temperatures of the dead family members.
At the same time, pathologist Alexander Dempster said, the core temperature of a body can only give a range of possible times of death.
Dr Dempster was giving evidence on Monday as to how David Bain's parents and three siblings were killed in Dunedin in 1994.
Bain is being retried for the murders after the Privy Council in London quashed his original convictions. He has pleaded not guilty to all charges.
Dr Dempster told the court he was made to wait outside the house for more than two hours before starting an initial examination of the bodies. By then, they'd been dead for at least six hours, which made it impossible to say how long each person had been dead.
But even the most accurate core body temperature test, he said, has a range of plus or minus 2.8 hours.
Stephen Bain asphyxiated before being shot
Giving evidence about how each victim was killed, the pathologist also gave details about the fight in Stephen Bain's room that ended in his death.
He said a post-mortem showed Stephen had been asphyxiated before being fatally shot in the head, and there were abrasions and bruises on his body.
Mr Dempster told the court he found three bullet wounds to Laniet Bain's head although the first one through her cheek would not have killed her, and she had survived for some time after the first shot.
The jury were again shown graphic images of the bodies and photographs of their bullet wounds as Dr Dempster explained what types of injuries he found.
One juror became visibly upset as the photographs were shown.
The defence maintains that David Bain's father Robin killed his wife Margaret and three of his children - Stephen, Arawa and Laniet - before shooting himself.
Dr Dempster's evidence continues on Tuesday.