Belfast-trained forensic pathologist James Ferris, now semi-retired in Auckland, said there were "some issues" that concerned him about the position of Robin Bain's body, which was lying on the floor near a curtained alcove in the front room of the family's Every St home.
He did not believe large splashes of blood and brain tissue on one of the curtains had resulted from the impact of the bullet entering Mr Bain's head, Prof Ferris told the High Court jury.
Although he was not a blood spatter analyst, his view was that because of the damage the bullet would have caused to the brain any blood and tissue forced from the wound would have been thrown out in tiny droplets.
"These are large splashes," Prof Ferris said.
To produce them, the already-sustained gunshot wound would have to be "dripping" down the curtain.
The nature of the wound meant Robin Bain would have collapsed immobile and dead, or dying instantly.
He would probably have dropped straight to the floor, although if he had been moving in a particular direction when he was shot, he might have continued moving in that direction "but not in a voluntary way".
The splashes could only have occurred "if the body had been moved and the blood was shaken out of the hole".
Prof Ferris was the third of three Crown pathologists to reject the defence suggestion Robin Bain committed suicide.
But he and Wellington forensic pathology specialist Kenneth Thomson both disagreed with Dunedin pathologist Alexander Dempster's view that the wound to Robin Bain's left temple was a close contact wound.
Dr Thomson believed the gun was fired from a distance of about 20cm.
Prof Ferris put the range at somewhere between 30cm and 42cm although, from his analysis of test fire results, he believed a distance of 38cm best illustrated the powder residue seen around Robin Bain's head wound.
If the firearm was discharged at that range, the wound could not have been self inflicted, he said.
"In my view, it would simply be impossible to self-inflict the injury we see and produce the pattern of powder marking on the skin."
A range of 38cm-42cm completely ruled out suicide, Prof Ferris told the court.
The only survivor of Robin Bain's immediate family, 37-year-old David Cullen Bain, is on trial for a second time for the murders of his father Robin, mother Margaret, sisters Arawa and Laniet and younger brother Stephen on June 20, 1994.
The Crown says Bain shot all five members of his family and placed the rifle beside his father to put the blame on him.
But the defence argument is that Robin Bain killed his wife and three of his children before shooting himself.
The trial which completes six weeks today, is being heard in Christchurch before Justice Graham Panckhurst and the jury of seven women and five men.
During his evidence yesterday, Prof Ferris told the court it was rare for a right-handed man, as Robin Bain was, to commit suicide by shooting himself in the left temple with a rifle.
When it did occur it was generally with a handgun.
About 70% of suicides with a rifle involved a shot into the mouth, with a smaller percentage into the neck and even fewer to the side of the head.
The gun could be in any position, as long as the person had access to the trigger, Prof Ferris said.
It was the range of the shot that was the most important factor.
He told the court he could not recall seeing a suicide with a firearm using a silencer.
Under cross-examination, Prof Ferris remained firm in his view that the wound to Robin Bain's head was an intermediate range wound.
He said he understood that was contrary to Dr Dempster's opinion and that experienced pathologists being called by the defence also disagreed with his view.
But he was expressing his opinion based on his analysis of the test firing results.
Evidence was also heard yesterday from police armourer Robert Ngamoki and Colin Taylor, the man who sold David Bain the Winchester .22 rifle in February 1993, the year before the Every St shootings.
Mr Taylor's statement of evidence said the 10-shot and 5-shot magazines were sold with the rifle and that he had often experienced misfires when using the 10-shot magazine.
Mr Ngamoki said the rifle had jammed once during the test firings he did.
He retained the projectiles and shell cases from the first five tests for the ESR and carried out another five test firings to test the rifle's accuracy and ejection.
He also fired the rifle to get test results at measured distances.
He explained how he cleared the rifle when it misfired (jammed).
Sometimes, the jammed projectile could be removed by retracting the bolt and shaking the rifle.
He had been asked to use gloves to test how difficult it would be to clear the rifle when it jammed.
"It was very difficult," Mr Ngamoki said.
He found it was better to remove the gloves and use his bare hands, a finger, as it was sometimes possible to flick the projectile out with a fingernail.
Otherwise, something like a ballpoint pen could be used.
Asked by defence counsel Helen Cull QC if the rifle was "prone to stoppages", Mr Ngamoki disagreed.
He had experienced only one during the test firings when he was using the 10-round magazine.
He said he was not aware the rifle had jammed five times on the morning of the murders.
To a suggestion a UK expert would say the rifle was prone to jamming with both magazines, the witness said the rifle had been sitting in the exhibit room for a long time and could be "not so reliable" when the defence experts tested it.
"That's the only reason I could see for it being unreliable," he said.
He told Ms Cull he believed it was possible to clear a jammed rifle in a few seconds without making much noise.
The defence argues if the rifle misfired before Robin Bain was shot, as the finding of a misfeed in the alcove behind the curtain suggested, the noise of the rifle being cleared would have been heard and it was unlikely Mr Bain would have remained where he was, waiting to be shot.
