A 27-year-old man has been found guilty of the murder of British backpacker Grace Millane whose body was found buried in a suitcase in New Zealand.

The young woman from Wickford was strangled by the man she had met on dating site Tinder and with whom she spent several hours drinking in the centre of Auckland on December 1, 2018.

The pair returned to his apartment and Ms Millane was killed either that night or in the early hours of the next morning - the date of her 22nd birthday.

The jury of seven women and five men returned a unanimous verdict after just five hours deliberation at Auckland High Court.

The Crown successfully argued the man, whose name is subject to a suppression order, strangled her and shoved her body inside a suitcase before burying her in a forested area outside Auckland.

She was assumed missing and her father, David Millane, flew to New Zealand as local authorities spent a week searching until her body was found by police.

Mr Millane and Grace's mother, Gillian Millane, wept after the verdict was delivered, as did several jurors.

The Millanes held hands as they left the court, with Mr Millane telling reporters the verdict would be welcomed by all of Grace's family and friends.

"It will not reduce the pain and suffering we have had to endure over the past year," he said.

"Grace was taken in the most brutal fashion a year ago and our lives have been ripped apart.

"Grace was our sunshine and she will be missed forever."

The defence had claimed the death was accidental and occurred during rough sexual intercourse.

The court had been told Ms Millane had an interest in BDSM, with a previous sexual partner testifying they had used safe words and physical tapping to indicate when physical pressure became overwhelming.

During the trial, the jurors heard from forensic experts who examined the accused's apartment for blood stains as well as Ms Millane's body after her death.

They were also shown footage of the woman and the defendant drinking at various bars throughout Auckland and kissing before they returned to his apartment.

Video footage from the elevator of her exiting on the third floor marked the last recorded time Ms Millane was seen alive.

Police officers said phone data showed the killer had used Google to browse websites for large duffel bags, suitcases and car hire after Ms Millane died.

The defendant's phone was also used to search for "flesh-eating birds" and "are there vultures in New Zealand?".

Records showed the defendant had searched online for "the hottest fire", "large bags near me" and "Waitakere Ranges".

On Friday the killer was remanded to custody until his sentencing on February 21, 2020.

He faces life in prison with a minimum of 10 years without parole, though the judge can increase the latter period.