Phillip Polkinghorne. Photo: RNZ/Nick Monro
Warning: Some readers might find this story distressing
A forensic expert has insisted her scene examination was "open-minded" during a cross-examination in the trial where a retired Auckland eye surgeon is accused of murdering his wife.
Phillip Polkinghorne denies killing his wife Pauline Hanna in their Remuera home in April 2021, and argues his wife struggled with her mental health, but their relationship was perfectly happy.
It is the second week of a six-week trial of Polkinghorne at the High Court in Auckland, and more forensic evidence was being heard, including the cross-examination of Environmental Science and Research (ESR) forensic scientist Fiona Matheson.
The Crown's case was that the couple were unhappy, that Polkinghorne was a "heavy" meth user who was living a secret "double life" with a prostitute and that finances had become a strain because of this - and that the combination of these factors led him to kill Hanna during a violent struggle which he then staged as a suicide.
During cross-examination, defence lawyer Ron Mansfield KC drew attention to Matheson being told by police to conduct the examination on the basis of a homicide at a briefing with police.
Matheson, however, insisted that her approach was open minded.
"I've considered both the hypothesis of it being a homicide, versus the hypothesis of it being a suicide, so it was very much in my mindset as I was carrying out the scene examination," she said.
Matheson said she collected lots of sampling - including of stains on clothing, bedding, DNA from cups and bottles, as she did not know how the investigation was going to progress and needed to ensure that they covered all the bases.
She said in her experience it was always easier to downgrade from an investigation than to upgrade, and that was why she took care from the start to capture all evidence.
Matheson said her scene examination took place between 5 April and 11 April, 2021, and that she returned to the scene for further visit on 15 April.
Questions were also asked about the details of the upstairs bedroom, where Polkinghorne said his wife had slept and was found in disarray the morning she was found dead.
The jury has earlier heard about a tipped over ottoman and a blood stain on a bedsheet which had Polkinghorne's DNA.
Mansfield asked Matheson whether there was blood detected anywhere else in the room, to which Matheson confirmed the only blood found in the room was on the bedsheet.
Matheson said there had been luminol tests done in the room to detect any blood that was not visible to the eye.
"There was also no blood on any of the walls?" he probed.
Matheson said that was correct.
"And you will know that if someone is struck, then sometimes you see blood splatter as a result of them being struck?" Mansfield asked.
"Yes, if a person is blood stained and an assault has occurred where there is an impact," said Matheson.
Last week, the court heard from Matheson that there were other probable blood stains detected in the house.
That included blood on a handrail of the staircase above where Hanna's body lay, in a bathroom and laundry around the edges of two drains.
The trial continues.
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