British backpacker Grace Millane was killed by accident during consensual sex, a court in New Zealand has heard.
The defence for the man accused of murdering the 21-year-old from Wickford, Essex, in Auckland last December said she died after being consensually choked during sex.
The 27-year-old man, who cannot be named for legal reasons, denies her murder and has chosen not to give evidence himself.
Last week, jurors were shown footage of the accused wheeling Ms Millane’s dead body out of his hotel in a suitcase.
It was alleged the man had organised another date while her body lay on the floor of his room.
Auckland Crown Court heard on Tuesday that Ms Millane had profiles on BDSM dating apps and had allowed a former partner to choke her during sex.
The accused and Ms Millane met through dating app Tinder and drank cocktails for several hours before returning to his hotel room at CityLife in Auckland, the court heard.
Earlier in the trial, a former partner of the accused said he had suffocated her during sex.
Prosecutors say the man strangled Ms Millane. He denies murder but admits shoving her body in a suitcase and burying her in bushland outside the city.
Defence barrister Ron Mansfield said: “If this couple engaged in consensual sexual activity which included pressure being applied to her neck with her consent and that went wrong, that is not murder.
“Death through this mechanism may thankfully be rare but it does happen and sadly it happened here.”
The court heard from police statements that Ms Millane had been using BDSM dating site Whiplr an hour before she met the defendant.
A former sexual partner of Ms Millane’s, whose identity has been suppressed, gave a written statement to the court saying the pair had tried choking during sex.
"When we researched it we knew the word was asphyxiation,” he said. "Grace and I discussed keeping hands wide and on the side of the neck, never on the front.”
He said the pair had a safe word or tapped the other person three times to indicate they wanted to stop.
Florida-based forensic pathologist Dr Fintan Garavan, appearing as a defence witness by video link, told the court Ms Millane died during consensual sexual activity including choking. He said the primary cause of death was asphyxiation.
He said there was "no evidence to injuries of deeper haemorrhaging" in Ms Millane's death.
He said a bruise found on Ms Millane's neck was not located in deep tissue, which along with further bruising on her chest and arms showed the injuries were the result of consensual activity.
"In my expert opinion, if a non-consensual act has taken place the victim is under attack or resisting attack, they struggle,” he said.
"It's that action, the struggle or struggling, between an aggressor and a recipient, that gives rise to such injuries."
The court heard Ms Millane’s alcohol consumption that night may have sent her heart into a “terminal tailspin” when she was choked during sex.
Dr Garavan said alcohol could "very well" have been a secondary contributing factor in Ms Millane's death.
The defence said she consumed four mango cocktails, one tequila shot and two whisky cocktails and also shared three half litre jugs of margaritas and sangria with the defendant.
Dr Garavan said the alcohol, along with the choking, was "an iceberg making its way into the shipping lane".
He said: "It very likely has become an important indirect player in causing death.”
The defence is expected to finish presenting its case on Wednesday. The trial continues.