The lead detective in the Grace Millane case says the defence's rough sex defence was a "cop out".
The British backpacker was strangled to death by Jesse Kempson in 2018, after a Tinder date in Auckland on the eve of her 22nd birthday.
A new feature-length film, The Lie, looks into the case and examines the rough sex defence used at Kempson's trial.
Kempson claimed he accidentally killed Millane after she asked him to choke her during intercourse.
He was found guilty of murder and sentenced to life in prison, and later convicted of sexual attacks on two other women.
Detective Inspector Scott Beard told Saturday Morning he did not agree with the rough sex defence, which had since been banned in the United Kingdom.
It revictimised not just Millane but also her family, including her mother Gillian who sat through every day of the trial, he said.
"Gillian was beside me crying and sobbing," he said.
"She was determined to stay, but it was so tough for her."
Gillian previously told the BBC that hearing the rough sex defence in court was "horrendous".
"I felt like Grace was on trial and she couldn't defend herself. As a parent, I didn't want to listen to that," she said.
"You can't ask for your own death. It is ludicrous this can be used as a defence."
Beard told Saturday Morning a law change in 2021 around what lawyers could ask victims of sexual violence went "a little way" towards banning the rough sex defence.
However, that law change was not applicable to murder cases.
"You can't strangle someone for five to 10 minutes and say that was rough sex. You feel them going limp. You'll know. And I'm sorry, it's murder."
Beard said it was up to parliamentarians, not him, to ban the defence, but if asked, he would support a law change.
The documentary's director, Helena Coan, said the rough sex defence was "abhorrent".
It was the "ultimate lie" referred to in the film's title, she said.
"I think it is the most offensive use of the justice system.
"I think it is a very clever and manipulative way of harping on that same tune - she asked for it."
The defence's legal team said in court that Kempson was "just doing what [Millane] wanted him to do, or what she asked him to do", Coan said.
"I think the fact that that's allowed is disgusting."
The way Millane was portrayed in court spoke to a wider issue around violence against women, Coan said.
There was still a tendency to blame the victim, rather than looking at the aspects of society that contributed to women's murders.
She wanted to make the film in a "sensitive and compassionate way but also an honest way", she said, and centre women's stories.
That included the stories of other women who dated Kempson.
Coan also liaised with Gillian, through Beard, before making the film, and received her blessing.
"If she had turned around and said 'don't make it' I would never have done it."
The film will be released in cinemas on 25 April.
RNZ
