Murder accused Cory Jefferies told police he didn't think his partner wore her Fitbit during the period before she went missing.

In a police DVD interview with Detective Constable Janine Post played to the High Court at Hamilton today, Jefferies also said cellphone reception in the Arohena, South Waikato, area where they lived was often poor and could take a couple of days to get text messages or alerts to missed calls.

Jefferies denies a charge of murdering Richmond, his partner of 26 years.

However, he does admit causing her death but says it was unintentional.

Richmond, 42, was missing for 11 months before her body was found inside their Ford Ranger which had been dumped in Lake Arapuni.

The couple had been socialising with other locals at the Arohena Hall in South Waikato when a fight broke out in their car on the way home sometime after 3.39am.

The Crown alleges Jefferies, 46, was an enraged, jealous partner who had told various people on different occasions that he wanted to "f****** kill the bitch" and he wanted "her gone".

Jefferies' DVD interview from August 19 was today played to the court.

He said she didn't wear her Fitbit as often as she used to and wasn't sure if she was wearing it the night she disappeared as she was wearing a jacket.

"She used to wear it all the time when she first got it but it petered out a bit."

She had owned it for between six months or a year, he told Detective Constable Janine Post, the interviewing officer.

Jefferies said he texted Richmond at 1.22pm on the Sunday, the afternoon of her death, asking "what time are you back?"

He said he also texted her good friend Barbara Cottingham and then her mother the next day.

Their children also called and texted their mother, pleading for her to come home.

"Hi it's [daughter] where are you because I need you home here."

Asked about the mood at the end of the night at the Arohena Hall, Jefferies said it was the same from earlier on.

"Just cruising along having a few drinks."

 

Kim Richmond was a champion at table tennis but loved all sports and was about to start training for a marathon before her death in July 2016. (Photo: NZ Herald/Supplied)

THE AFFAIR
Yesterday, the man at the centre of the affair, Alfons Te Brake, explained how things became romantic in November 2015.

He said there had been kissing and cuddling between himself and Richmond on several occasions.

He recalled a couple of incidents in the following months when he was approached by Jefferies about an affair.

The most recent before her death was on July 9, 2016.

"[Jefferies] mentioned along the lines that he was going to f*** up my life and Kim's. I said, 'You go and help yourself.' I didn't ask him how he was going to do it."

CHANGING THE TRACK

Detective Craig Lemins told the court that Jefferies said the argument in the car home on the way home started after he changed the music from The Feelers CD to a radio station.

"I changed it to a different song," he said in his statement days after her disappearance. "Kim replied 'why don't you change it back to what it was."

He said he drove them home, parked their Ford Ranger, hung the keys up in the kitchen and went to bed.

He then watched, a few minutes later, as Kim got in the truck and drove out of the driveway.

BUSTED BY TECHNOLOGY

The Crown say it was a combination of tracking from the couple's cellphones and Richmond's Fitbit which helped them close in on who was responsible.

Her Fitbit recorded a period of elevated heartbeat between 3.30am and 3.39am as the couple helped tidy the hall before they set off and it calmed down.

Her last recorded heartbeat was at 3.43am.

After stopping on the side of the road, about 120m from home, cellphone records helped detectives track Jefferies' phone as it travelled to Lake Arapuni before it headed back home.

However, the tracking revealed it was moving much slower - at walking pace.

Jefferies eventually reported her missing on the Monday when he contacted Richmond's mother, Raywynne, asking if she had heard from or seen her daughter as he hadn't seen her since early Sunday morning.

WAS IT MURDER?

Defence counsel Tom Sutcliffe told the jury on Tuesday that just because his client accepted responsibility for Richmond's death it didn't mean he meant to cause it.

"It does not mean that he meant to cause her bodily injury that was known at the time be likely to cause her death.

"What you can accept ... is that the defendant is responsible for Kim Richmond's death. The defence say that in that instance that Mr Jefferies is therefore guilty of culpable homicide in that he committed the offence of manslaughter not murder."

He told the jury the issue was one of intent.

"The test is what his state of mind was at the time."