Two forensic pathologists walk into a bar. One is from Christchurch, and has a long, gaunt face, given warmth by a moustache. Another is English, living in Ottawa, with white hair raked forward on his pink happy face. They meet at a medical conference in America. They order drinks. If the bar was dead, they’d feel at home; together, they have conducted at least 2000 autopsies. They may or may not make small talk but sooner or later they get around to the thing that consumes their professional lives, the big sleep. Martin Sage, the New Zealander, says to his colleague, Christopher Milroy, "Have you ever seen a death by compression of the neck with no internal or external injury? Because I’ve just got one."

The case was the death of Pauline Hanna, 63, on April 5, 2021, at the Remuera home she shared with her husband, Dr Philip Polkinghorne. The bar-room conversation was relayed at the High Court of Auckland on Tuesday. Milroy was called as a defence witness in the murder trial of Polkinghorne, accused of strangling his wife to death, maybe in a choker hold, and then allegedly carrying the body downstairs to stage a suicide by hanging. Polkinghorne is 71. He sat in the courtroom modelling pink polka-dot socks on Day 28 in the seventh week of a murder trial that has been the subject of much excited national chatter from late winter to early spring. Wisteria in the High Court courtyard has flowered; ginko trees lining the nearby avenues are now in light, lovely leaf.

Philip Polkinghorne appears in the High Court in Auckland. Photo / Jason Oxenham

The prosecution case took four weeks. Sixty witnesses were called. The defence is in its third week and Justice Graham Lang’s expressed hopes last Friday that he would be able to sum up the trial this Friday are looking woeful. Perhaps this thing will never end. It often feels that way during the long, cheaply air-conditioned days in Courtroom 11.

Milroy appeared by videolink. His white lab coat hung over the door. Books and papers were scattered in charming piles in his office. His phone rang; he laughed, and said, "I’m on call and I’m being paged but I’m going to ignore it. It’s never that urgent in forensic pathology." Death is patient. Anyway, then he got down to business, and, in answer to defence lawyer Ron Mansfield who asked him what he would have said was the cause of Hanna’s death, he replied, "I would have given cause of death as hanging." And: "The most likely cause of death was hanging by partial suspension." Also: "I’m aware of ideas about some other form of neck compression, with a cover-up by suspending the victim after death, but I don’t have any concerns about having an opinion of death by hanging."

We have been here before, late last week, when the defence called another forensic pathologist, Dr Stephen Corden. He was equally confident in stating death by suicide. Two expert opinions which are extremely unsympathetic to homicide is a strong hand to play. But Milroy was actually a late addition to the defence case; the court heard on Tuesday that he provided his report as recently as August 21, nearly four weeks into the trial. He was approached to bolster the defence case after Corden’s findings were challenged by Martin Sage, the moustachioed Dr Death who was Milroy’s drinking buddy in an American bar.

One of the earliest police suspicions about Hanna’s death was that the ligature mark around her neck – Polkinghorne claimed he found her lifeless body slumped forward on a chair, hanged by a belt and a rope – had disappeared when forensic pathologist Dr Kilak Kesha examined her the next day. Corden, though, testified last week that it was meaningless, and Milroy agreed: "The point is that it’s not an injury. It is simply an impression. We’d expect it to disappear."

The more profound issue, he said in the witness box, was the lack of internal or external injuries to Hanna’s neck. It was this absence which occasioned Sage’s conversation starter with Milroy over a drink. The two forensic pathologists agreed it was an extremely rare event – the lack of neck injuries in a homicide by strangling, not having a drink. Sage could only think of one case in his entire career. Milroy could only think of one, too. The victim was a 14-year-old girl put in a choker hold. But in all other cases – in his own experience, and in the literature – every single strangling death caused internal or external neck injuries. There were none on the surface of Hanna’s neck. Mansfield asked Milroy, "Did Kilak Kesha dissect her neck to look for internal injuries?"

He replied, "Correct."

"And he found none?"

"Correct."

Philip Polkinghorne and his lawyer, Ron Mansfield, KC, arrive at the High Court. Photo / Michael Craig

Milroy’s white hair fell forward in two strips, like an 11 on his head. He was almost cherubic. He said, "If I have concerns about a suicide by hanging, I will do an internal exam, and if I don’t find anything, an absence of injuries, that makes me more confident of a suicidal hanging." His smile indicated he was very confident indeed. He spoke fluently, and in perfect sentences. In cross-examination by Crown solicitor Alysha McClintock, though, he ummed and ahhed, and smiled considerably less.

McClintock has argued in court that Polkinghorne may have attacked his wife while she was heavily sedated on alcohol and an anti-depressant drug. She put the combination to Milroy: "A double whammy, if you like."

He did not like. He replied, "Well, one interacts with the other."

She questioned him on how much alcohol she had in her blood. Milroy said tests determined it was at a low level at the time of death. "We can be confident of that," he said.

She asked, "But not when she went to bed?"

He could not be confident. "No," he said.

She returned to her theory that Hanna was attacked, and unable to struggle. Milroy agreed that it’s possible for a victim to lose consciousness after only 10-15 seconds if thorough and consistent pressure is placed on the neck. She asked if it took another three or four minutes to cause death. He said, "I think that’s a bit long. I think it’s shorter. A minute or two."

A life extinguished, quickly and brutally. Milroy was asked by both McClintock and Mansfield if he had ever known of a case where a homicidal strangling was performed by a surgeon. He did not. He was also asked if a surgeon would have the requisite forensic experience to know how to strangle someone without leaving internal or external injuries. "I would not expect a non-forensic practitioner," he said, "to have any skills in that area."

Polkinghorne watched Milroy on the videolink screen suspended above the court and seemed quite content to be called an ignoramus.