Warning: The Grace Millane murder trial is hearing evidence of a graphic and sexual nature. Reader discretion is advised. The trial is taking place in open court and media are required to accurately report the evidence as it is presented.

"We are here to investigate how Grace Millane died," Ron Mansfield told a jury yesterday.

He is one of a three-pronged legal team defending a 27-year-old man charged with murder.

No one would believe the accused's story of a fatal sexual misadventure after matching on the online dating app Tinder, Mansfield said.

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"But don't prove him right," he urged the High Court jury.

The case of the man accused of murdering the British backpacker on the night of December 1 last year in Auckland continued into a third week.

It began with the alleged killer's chief defence lawyer, Ian Brookie, informing Justice Simon Moore that his client will not give evidence himself but elects to call evidence.

The testimony included an expert forensic pathologist, some of Millane's friends and evidence of her online sexual behaviour.

During the defence's opening address yesterday, Mansfield said the accused and Millane were an "otherwise happy couple, having fun, and consensual sex" on the night of December 1.

CCTV footage of the pair shows them drinking, laughing and kissing throughout the evening.

Crown prosecutors allege that on the eve of Millane's 22nd birthday the accused strangled her to death in his CityLife hotel apartment in downtown Auckland.

Mansfield, however, said the Crown had shown no evidence of "some assault, for which we have absolutely no motive for".

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"None of the people who were occupying the room right next door heard any disturbance," he added.

What the accused did after Millane died, which included disposing of her body, cleaning the apartment, dumping evidence and lying to police, was the result of fear, Mansfield said.

"People do things when they're stressed, when they're panicked.

"No matter what he did once he realised she had died, unless he called the authorities, that was not going to look good or stand him in good stead ... Because who was going to believe him that death occurred during a consensual sexual activity?"

Grace Millane murder trial: Accused admits to disposing of body. Video / Chris Tarpey

But as reprehensible as the accused's conduct in the days after may seem, Mansfield said it would tell the jury little about how Millane died.

"In this trial, like it or not, we have no choice but to confront what happened in [the accused's] bedroom at the CityLife that night. Because that is where we know Ms Millane died. And we are here to investigate how Ms Millane died."

He said this included evidence about Millane's sexual preferences, just as the accused's and "his life through Tinder" had been canvassed by the Crown.

"I want to be very clear that no one is trying to shame Ms Millane or her family and no one is trying to blame Ms Millane and her family," Mansfield said.

Millane, he continued, was a "loving, bright, engaging, intelligent and well-liked woman".

"That is her reputation and that should be her reputation and memory at the start of this trial and at the conclusion of it."

A former sexual partner of Millane's had his statement read to the court, in which he talked of their relationship and how she enjoyed choking during sex.

Grace Millane died on the weekend of her 22nd birthday. Photo / Supplied
Grace Millane died on the weekend of her 22nd birthday. Photo / Supplied

The pair, he said, also practised BDSM, blindfolding and role play.

But, the statement continued, the two trusted each other and used a safe word.

"Grace and I were careful to discuss not only the physical but psychological effects of BDSM."

A friend of Millane also had her statement read to the court.

The confidant said part of "girl talk" included the two discussing their sexual preferences.

Millane "enjoyed her partner putting his hands around her neck", BDSM and rough sex, she said.

The court also heard evidence that Millane held accounts on Whiplr and FetLife, online BDSM and sexual fetish communities.

She last accessed her Whiplr account on December 1 last year - the day she met the accused - from her backpackers in Auckland.

Mansfield earlier told the jury not to make assumptions about the evidence based on their own beliefs.

"In this trial, if we're not careful, our own religious, political, social or moral views can distract you."

The accused's defence team of Claire Farquhar, Ian Brookie and Ron Mansfield. Photo / Michael Craig
The accused's defence team of Claire Farquhar, Ian Brookie and Ron Mansfield. Photo / Michael Craig

Later in the afternoon the court listened to pathologist Dr Fintan Garavan via video link in Miami in the United States.

Garavan said the "major participant" in Millane's death was pressure on her neck - corresponding with the finding of the Crown's expert pathologist Dr Simon Stables.

He, however, disagreed with Stables' position that alcohol would not have been a factor.

Millane's alcohol consumption may have led to a biological "safety valve" not kicking in, Garavan said.

The expert in the effect of drugs and alcohol on the body added it could "very well have been a secondary factor in the cause of death".

CCTV shows the backpacker had several drinks on the night she died, including shots of tequila and cocktails.

The doctor said the narrative of rough sex from the accused was also "an adequate" explanation as to how Millane may have died, given the bruising found around her neck.

Today the court is expected to hear evidence from a private investigator hired by the accused's legal team.