A pathologist has told the David Bain retrial that it would be difficult to pinpoint when the accused's sister Laniet stopped breathing.
David Bain, 37, is accused of shooting his father Robin, mother Margaret, brother Stephen and sisters Arawa and Laniet in their Dunedin home on 20 June 1994.
The defence says Robin Bain killed the family members present in the house before using the accused's rifle to shoot himself.
David Bain told police he heard gurgling from Laniet's room, which the Crown says that was a sound only the killer could have heard.
The Crown says the sound may have caused David Bain to go back into Laniet's room to fire the third fatal shot.
Pathologist Alexander Dempster told the High Court in Christchurch on Tuesday it is likely Laniet continued to breathe after the first shot, before being shot two more times.
But under cross-examination on Wednesday by defence lawyer Michael Reed, QC, Dr Dempster said he could not rule out the possibility that she kept breathing after the third shot.
Other gun positions 'possible'
Earlier, Dr Dempster, who concluded it would be unlikely that Robin Bain shot himself, conceded under cross-examination that it would be possible if the gun were held in a different position.
Dr Dempster told on Tuesday that the trajectory of the bullet found in Robin Bain's head and the angle of the entry wound made it possible, but unlikely, that the shot was self-inflicted.
On Wednesday, Mr Reed showed Dr Dempster a series of photographs with the rifle used in other positions as defence experts simulated the way Robin Bain could have shot himself.
Seven options of how a rifle could be held by a right-handed person in order to shoot himself in the left temple were produced by the defence.
Dr Dempster conceded that in each scenario it was possible to fire the weapon. In one case, he expressed surprise at how much easier it seemed for the model to reach the trigger.
Police initially considered the possibility of murder-suicide by Robin Bain before they charged Mr Bain with murder.
Dr Dempster, who conducted the post-mortems, told the court on Tuesday that the bullet that killed Robin Bain went into his temple at a 45-degree angle.
He said it would have been difficult, but not impossible, for Robin Bain to shoot himself at that angle using the rifle with a silencer attached. However, he said it was "a very unusual wound for a self-inflicted wound".
Dr Dempster said he is the same height as Robin Bain, and when he tested the theory, he could only reach the trigger with the middle finger of his left hand.