Xue's lawyer raises sex act theory

Nai Yin Xue is accused of killing wife An An Liu (top right) and leaving daughter Qian Xun Xue, also known as 'Pumpkin', at a Melbourne train station. Photos / Paul Estcourt / Supplied

A lawyer for Nai Yin Xue has raised questions in his High Court murder trial about whether an accident in a sex act could be responsible for his wife's death.

Prosecutors say Xue, 55, strangled his wife, An An Liu, who was found dead in the boot of his car on September 19, 2007 in Mt Roskill. They say she died eight days beforehand.

Pathologist Timothy Koelmeyer told the court today he believed Ms Liu was probably strangled from behind using a neck tie found around her neck when her body was discovered.

But Xue's lawyer Chris Comeskey asked Dr Koelmeyer several questions about auto-erotic asphyxiation, and whether it was possible Ms Liu died accidentally.

Dr Koelmeyer said auto-erotic asphyxiation was a sexual practice often associated with complicated bindings, where the reduction of oxygen to the brain was said to increase a sexual high.

If it involved other people, the term "auto" would not be used.

Dr Koelmeyer said he was aware that death had been known to occur in these cases, and he had been involved as a pathologist in the case of Peter Plumley-Walker, who died after a sexual episode involving bondage.

When asked by Mr Comeskey if accidental asphyxiation could not be ruled out, Dr Koelmeyer was hesitant to answer, saying it was really a matter for the jury.

"If I was really pushed in a corner, I would say I can't rule out an accident, but I don't favour it."

When answering subsequent questions from prosecutor Aaron Perkins and the judge, Justice Hugh Williams, Dr Koelmeyer reconfirmed an earlier answer that a person who became unconscious after being strangled would need pressure to continue to be applied to die.

He said this would be difficult for an unconscious person to do to themselves and would probably have to come either as a result of the object around someone's neck being attached to something such as a hook, or from an assailant.

The crown alleges Xue strangled Ms Liu probably on September 11, 2007, and then fled to Melbourne two days later with the couple's three-year-old daughter, Qian Xun Xue.

They say he then abandoned Qian Xun at a Melbourne train station before flying to the United States. He was apprehended there about four months later.

The trial in the High Court at Auckland is into its third week.

- NZPA