An expert witness has told the High Court in Auckland that he could not rule out accidental asphyxiation as the cause of An An Liu's death.
However, pathologist Timothy Koelmeyer says he does not favour it as an explanation.
Nai Yin Xue, 55, is on trial for the murder of his 28-year-old wife in September 2007, before abandoning their three-year-old daughter in Melbourne.
Qian Xun Xue, then aged three, was found alone at Melbourne Railway Station a few days before her mother's body was discovered in the boot of a car in Auckland. Her body was found with a man's tie tied around her neck, and also across her eyes.
A defence lawyer, Chris Comesky, asked pathologist Timothy Koelmeyer if he knew about the practice of auto-erotic asphyxiation, a sexual practice that involves restricting the airwaves.
Mr Koelmeyer said he knew of the practice, but did not favour it as an explanation in this case.
He also said it was impossible to say when Ms Liu died. The Crown says she was killed on 11 September 2007 and Mr Xue left the country in the following days. Her body was not discovered until 19 September.
Mr Koelmeyer told the court on Tuesday that predicting the date of her death would be like witchcraft. He says the most accurate he can be is to say that Ms Liu died between the time she was last seen alive and the day her body was found.