Police give evidence in Philip Polkinghorne on day three of murder trial. Video / NZ Herald
WARNING: DISTRESSING CONTENT
The trial of Philip Polkinghorne, accused of killing his wife at their Remuera home and staging the scene to look like a suicide by hanging, has heard evidence from a Canadian rope expert who supports the police contention that the rope could not have handled the weight of a person.
But Polkinghorne’s lawyer, Ron Mansfield, KC, gained several concessions from forensic rope expert Robert Chisnall, with the Canadian agreeing the shape of the rope indicated it could have been partially untied by the distressed ophthalmologist after what he says was her suicide by hanging.
Polkinghorne, 71, is accused by prosecutors of having strangled Pauline Hanna, 63, inside their Remuera home – possibly while high on methamphetamine and during a heated confrontation over finances or his expensive extra-marital affairs with prostitutes – before staging the scene to look like a suicide.
The Crown has acknowledged the case against Polkinghorne is circumstantial, meaning there are numerous small pieces of evidence that they have predicted will fit together like a jigsaw puzzle to form a complete picture of what occurred.
The defence, meanwhile, has said police had a fundamental misconception about what had occurred from the get-go, leading to a biased investigation that resulted in a murder charge 16 months later despite no solid evidence to support it.
Chisnall, who appeared via a visual link from his home in Ontario, was the main event of day four of the murder trial on Thursday and a key expert witness for the Crown.
The day before, the jury heard of a “tension test” conducted by a detective on the morning of April 5, 2021, after Polkinghorne had called 111 to report what he said was his wife’s suicide.
Sergeant Christian Iogha told the jury the test, which he had conducted several times before at suicides, to assess whether the rope could support Hanna’s weight to the degree required for suicide by hanging.
The orange rope tied to the balustrade inside the Polkinghorne home, which the eye surgeon said his wife used to kill herself, has been a focal point of evidence in the first week of his trial.
As a result, he and other detectives became suspicious about the explanation offered by Polkinghorne and began treating the death as suspicious.
Chisnall said he did not have the precise rope but reconstructed its shape using a similar rope and photos police took at the scene.
He said he used the ropes and his back porch to try to reconstruct how the rope was tied.
”I wanted to verify how insecure the knots were,” he said.
”Multiple times I pulled on the rope ... the results were the same all the time.”
Polkinghorne told police he undid the “granny knots” upstairs after getting his wife down and undoing the belt and rope from around her neck.
He said he undid the rope upstairs because it looked “hideous” hanging above the landing.
Mansfield, in his cross-examination of Chisnall, questioned if the rope expert had asked to examine the actual rope and balustrade, which the Institute of Environmental Science and Research (ESR) and police secured and removed from the scene. He said he did not.
He conceded he did not have an engineering degree, instead holding a Master’s degree in education and a BSc, but said he had extensive experience with rope from teaching rock climbing and rope access and had authored a text on the subject.
Chisnall said he assessed a slippage in the knot to be at least 6cm.
Philip Polkinghorne and his lawyer, Ron Mansfield, KC, arrive at the High Court at Auckland for day three of Polkinghorne's murder trial. Photo / Michael Craig
The unknotted end of the rope appeared to have “knot memory” or residuals twists indicating it had been unknotted, he said, appearing to support Mansfield’s contention that his client at least partly undid the rope at the top of the stairs.
Later on Thursday, Sergeant Iogha returned to the witness box, where Mansfield cross-examined him on the state of the scene in the bedroom where Pauline Hanna slept.
An ottoman was tipped over and the room appeared dishevelled, which the Crown suggests shows signs of a struggle before Hanna’s death.
A brown stain on a fitted sheet was identified as likely to be blood, and the bed was missing a top sheet. In a dryer, police found a top sheet.
Polkinghorne also had a small fresh wound on his forehead when police arrived.
Iogha agreed with the KC that if Hanna had been killed in a struggle in the bedroom, she would have needed to be dragged across the bedroom and down the stairs to the landing where her body lay when paramedics and police arrived.
”And as I understand it from the very careful examination of this room,” Mansfield said, “... there were no indications other than what you have told us of any blood being identified in that room either by way of a visual examination or a luminol testing that was considered to be relevant?”
Sergeant Iogha confirmed there was nothing of that nature beyond the brown stain on the fitted sheet.
Nor were there any signs of Hanna having been dragged across the carpet, Iogha said in response to Mansfield’s questioning.
The KC continued to press Iogha on the lack of evidence for how Hanna might have been moved from the bedroom, where the Crown says there were signs of a struggle, down the stairs to the landing where she was found.
”There was no evidence seen on examination or forensically to tell us how that might have occurred?” Mansfield asked.
”Yes that’s correct,” Iogha said.
The sergeant also agreed that beyond the brown stain on the fitted sheet that tested positive for blood, there was no evidence of an assault by way of blood or bodily fluid.
While there was no damage in the bedroom, its state of disarray was strange, Iogha said.
”No damage as such but, it’s just very odd to see a room in that state after someone has just taken their own life,” he said.
The trial will resume on Friday morning at the slightly later time of 10.30am, with more cross-examination of Sergeant Iogha.
Then the Crown is expected to call several expert witnesses including ESR forensic scientists.
THE ROPE IN THE LANDING
“When I got her down it looked too hideous to me. I undid the granny knot upstairs. It looked awful just hanging there. It was just horrible, the rope.”
That was the explanation eye surgeon Philip Polkinghorne gave to police on April 5, 2021 – just hours after the reported suicide of his wife started to be instead treated as a suspicious death – about why the bright orange rope found dangling near her body was unexpectedly loose when investigators arrived.
The statement, from a yet unplayed three-hour police interview, was read aloud by Polkinghorne’s lawyer today as the Crown continued to call evidence on the fourth day of Polkinghorne’s six-week murder trial. It was intended to rebut the findings of a Canadian knot expert who spent the entire first half of the day testifying via audio-video feed from overseas.
Robert Chisnall, who has published papers and authorised a manual on knot-tying for forensic investigators, came up with a simple conclusion: the rope, as police found it tied, could not have been used in a suicide by hanging.
“It was an insecure grouping of tangles with additional slack on the floor,” he said. “It was too long and too insecure to suspend any weight.”
Pauline Hanna and Philip Polkinghorne at an event in December 2018. Photo / Norrie Montgomery
A series of “granny knots” were tied across three balustrades at the top of the stairs. The knot had not slid down to the base of the railing and could easily be moved up and down when given a slight push, the investigators testified.
The knot expert drew detailed sketches of the knot and recreated it at his home in Canada using multiple varieties of rope he had in storage. He used two different balustrades – one on his back deck – then conducted more than 20 tests to see how the rope and the knot reacted.
“Very little force was required to cause it to collapse,” Chisnall testified, explaining that he yanked on the ropes while using a luggage-weighing device to calculate the amount of force needed to make the knot slide down the balustrade. “The force didn’t even register on the gauge. It was under 1 kilogram.”
The witness disagreed, under cross-examination by Mansfield, that having the actual balustrade and rope for his experiment would have changed the outcomes. He could have tied any rope to any balustrade and, given the way the knot was tied, it would have reacted the same way, Chisnall insisted.
But Mansfield also suggested during cross-examination that the expert didn’t have all the evidence necessary to reach a conclusion. He noted that Polkinghorne told police and the 111 operator on the day of his wife’s death that he had loosened or undone the knot shortly after finding his wife and cutting the other end of the rope.
It made sense that someone trying to undo a knot would lift it up the balustrade for easier access if it had slid down during a hanging, Mansfield suggested.
He also noted that the knots used to secure the rope were relatively simple, while Polkinghorne’s knowledge of complex knots would have been second nature. The defence played animated videos of surgical and simple knots to show jurors the difference.
A photo of rope from inside eye surgeon Philip Polkinghorne's Remuera home was entered into evidence at his murder trial in the High Court at Auckland. He is accused of having strangled his wife, Pauline Hanna, then staging the scene to look like a suicide by hanging.
Adding confusion to the matter, two ropes were found at the scene – another one was left in a jumbled mess on the stairs next to Hanna’s body. That might have been the actual rope Hanna used to hang herself before her husband cut it down, Mansfield suggested.
The lawyer noted that, although it was not in the expert’s report, Chisnall had sent an email to authorities early on noting that the rope on the stairs had some kinks in it that might possibly match the three bannisters upstairs. Chisnall said there wasn’t enough evidence to know for sure, which is why it wasn’t included in his final assessment.
“I thought it was the only piece of rope,” Polkinghorne told police, according to a transcript read aloud by his lawyer. “I didn’t see the other one [still tied at the top of the stairs]. I thought I undid that.”
But everything was flustered as he reacted fast, he continued.
“I’ve never seen that [knot] up at the top, unless I lifted it up to undo it,” he continued to police. “I thought I undid it. I thought I got rid of it. I’m sorry, I can’t help you any more.”
Craig Kapitan is an Auckland-based journalist covering courts and justice. He joined the Herald in 2021 and has reported on courts since 2002 in three newsrooms in the United States and New Zealand.
