A weapons expert from Britain has told the David Bain trial that tests he conducted on the gun used to kill family members showed it would have been easy for Robin Bain to have shot himself.
David Bain, 37, is charged with the murder of his parents Robin and Margaret and siblings Arawa, Laniet and Stephen at the family's house in Dunedin on 20 June 1994.
His defence says Robin Bain killed the family present in the house before shooting himself.
The Crown says suicide was not possible given the trajectory of the bullet in Robin Bain's head.
However, Philip Boyce, who has worked for police in the United Kingdom and Ireland and heads a forensic weapons centre in England, said various tests gave a different result.
He used the skull cap the Crown pathologist had designed which showed the exact angle the bullet entered Robin Bain's head.
Several different angles were attempted holding the rifle in different ways, including bending over the rifle.
Mr Boyce said in all the attempts it proved easy to reach the trigger and hold the rifle at the exact angle that it says Robin Bain held it to shoot himself.
Mr Boyce gave the jury a demonstration of how the defence believes Robin Bain used a rifle to shoot himself.
He held the the rifle to his head to demonstrate what he said were the three main ways in which it would have been possible for Robin Bain to shot himself.
In all three cases, Mr Boyce showed the jury that he could reach the trigger easily. Some of the jury stood to watch the demonstration.
Earlier, Mr Boyce stood in the witness box and replicated a rifle position demonstrated by a Crown witness. He said in that position he could not reach the trigger, and that he had never heard of anyone shooting themselves in that way.
The Crown says the arm span of Robin Bain and the length of the silencer on the rifle made it impossible for the 58-year-old to have shot himself.