A jury in Auckland has heard the closing arguments in the trial of a man accused of murdering Grace Millane, with the crown arguing he caused the British backpacker’s death by using “reckless violence”.

Millane died on the night of 1 December 2018 after a Tinder date with the accused, a 27-year-old New Zealand man whose name is suppressed. He has pleaded not guilty to murder. It is agreed that Millane died by strangulation in the accused’s hotel room in central Auckland, and that he later buried her body in a suitcase in a bushland area west of the city.

The crown prosecutor Brian Dickey said: “This case is about being strangled to death. You can’t consent to your own murder.”

Dickey said the New Zealand forensic pathologist who conducted an autopsy on Millane testified that it would have taken five to 10 minutes for her to die by manual strangulation, and that it would have taken “sustained effort and strength”, with her first falling unconscious and going limp before dying.

The accused showed “reckless intent” by squeezing Millane’s neck with such force and for so long, the crown argued, and not stopping when she lost consciousness. Showing reckless intent is grounds for a murder conviction in New Zealand.

“This isn’t a little bit of sex gone wrong,” Dickey told the jury. “There is powerful evidence in this case that Grace was murdered … because the person doing that must have known that they were hurting her, causing her harm, that might well cause her death, but they were reckless and carried on, and she died.”

In its closing address the defence disagreed, saying Millane died by accident after encouraging the accused to choke her during intercourse, and the pair were inexperienced at BDSM, had drunk a lot of alcohol and were carried away by passion.

The defence lawyer Ian Brookie said: “It’s not a dangerous act, and they were not thinking of it as a dangerous act, they were just thinking of it as having sex.”

Dickey described the rarity of death from strangulation during sex, recalling a pathologist’s evidence that it was “incredibly rare” globally and there had never been a case in New Zealand.

Dickey said the accused’s behaviour after Millane’s death proved he was unmoved by what had happened, and that he took sexual gratification by photographing her body – rather than showing concern, compassion, or empathy, by ringing the emergency services.

The defence said the accused’s actions following Millane’s death showed he was “panicking” and was afraid he would not be believed and go to jail. “When confronted with the crisis of this unexpected, unforeseen and unintended death the defendant freaked out … he reacted badly” Brookie said.

The crown said extensive CCTV evidence gathered the next morning showed the accused displayed no signs of being “panicked” but instead demonstrated “focus and nonchalance” as he travelled around Auckland in a hire car buying a large suitcase to dispose of Millane’s body, cleaning products to remove blood stains from his room, and setting up another Tinder date while Millane’s body remained in his room.

Dickey told the jury: “He was cool, calm, in control … it speaks to someone who was entirely without regret.”

The prosecution said the accused began telling ever more elaborate lies in a series of police interviews, initially saying he parted ways with Millane at 8pm on the night of her death, before changing his story and admitting sex with her in his hotel room, but not choking or killing her.

He also did not admit to Google searches for rigor mortis and flesh-eating birds in New Zealand, watching porn or taking photos of her body.

This, the crown claimed, was evidence he was attempting to conceal a murder rather than an accidental or tragic death.

The defence did not explain the accused’s conduct in the police interviews, but focused on him co-operating with detectives by eventually leading them to the shallow gravesite in the Waitakere ranges, where he had disposed of her body.

The defence said the photographs of the deceased were in fact taken while she was alive and that Millane had also taken photos of him but he had thrown away her phone, something they said was “a bad move”.

Previous sexual partners of the accused testified that he had an interest in choking, and one said she was “terrified” when he sat on her face and smothered her. A number of women the accused met through Tinder later cut off contact with him because he made them feel “uncomfortable”. The defence said the accused’s knowledge of choking was gained only from women asking them to perform the act on them, and was motivated by a desire to please them.

The crown said the defence had attempted to muddy the water by claiming a verdict of murder could be reached only if the accused had intended to murder Millane. Dickey stressed that the grounds for murder in New Zealand included displaying “reckless intent” and that on these grounds the accused should be found guilty.

“The defendant was causing harm that was likely to cause death … he was aware of that risk and that he took it. You kill somebody by conscious risk-taking, in this country, that is murder.”

The jury is expected to be sent out to deliberate on Friday morning.