A man on trial for murder told his former partner how his co-accused “just lost it”, court has heard.

Sean Hayde and Gregory Hart, both aged 35, have pleaded not guilty to murdering Wiremu Arapo, and attempting to pervert the course of justice by setting fire to Arapo’s Cockle Bay house. They each blame the other for the murder.

Hayde faces additional charges of strangling a former partner, assaulting her and threatening to kill her.

The Crown says Hayde and Hart each had motives to murder Arapo. Hayde had recently begun a relationship with a friend of Arapo’s, and Arapo did not approve. Hart was Arapo’s flatmate and regularly failed to make rent and bill payments and Arapo wanted him to move out.

Hart’s former partner, Charlotte Kozanic, told the High Court in Auckland that during their relationship Hart would act “quite immature – like an 18-year-old” – when he was around Hayde” and drink a lot more than normal.

She and her current partner visited Hart at his parents’ Papatoetoe home in December 2020, two months after the fire and days after he had been released on bail.

She said Hart described prison as “a lot of weird c…s screaming and asking you for nicotine lozenges.”

She recalled asking Hart about Hayde.

“Greg [Hart] said: ‘I don’t know, I told them to keep him away from me.”

Kozanic said by “them”, Hart was referring to the police.

At that point, Hart paused and got out of his chair before saying: “Sean just lost it. Sean and Wiremu never liked each other, they hated each other.”

Kozanic was asked by Crown prosecutor Ned Fletcher what Hart’s demeanour was like.

“It was like he was letting out a secret.”

Under cross-examination from Hayde’s lawyer Julie-Anne Kincade KC, Kozanic confirmed Hart had made no mention of any problems he had with Arapo.

Kincade asked if Hart had mentioned he hadn’t been paying rent, that Arapo was “fed up” with him and was looking to evict him from the flat. Kozanic said Hart had never told her any of that.

Under cross-examination from Hart’s lawyer, Paul Borich KC, Kozanic confirmed Hart had never said anything bad about Arapo. In contrast, she agreed Hart had always looked up to Arapo and that they were good friends.

She said she clearly recalled Hart’s comment about Hayde “losing it”.

“I felt sick knowing I knew that,” Kozanic said.

Earlier Crown prosecutor Amy Fry read the statements of Nicholas Sawers and Aniwhakaruru Sawers –the step-father and mother of Wiremu Arapo.

They spoke of their son as a people-person, a man with talent and a bubbly personality, who never held a grudge and had many options in life.

Nicholas Sawers said four days after his son was killed, he and the family were allowed back on to the property. They wanted to pick up their son’s valuable gym equipment which had been in a large garage near the house.

While they were there, Hart showed up on the driveway.

“He was shaking and upset… his voice was shaky and emotional,” Nicholas Sawers said.

He asked Hart to explain what happened.

Hart responded: “I’m not too sure, I’ve got my book, and I’m writing it down as I remember it.”

Nicholas Sawers said Hart told him how he and Hayde had arrived at the house to find Arapo playing his Play Station. Arapo offered them a spot of marijuana and had knives and an ounce of the drug on the kitchen bench.

He said Hart told them he declined the offer and went back to his room. He then described seeing a lot of smoke in the hallway but didn’t give further details.

“I said: Greg, look, I’m sorry, we weren’t trying to intimidate you. We want answers, and it doesn’t make any sense how he didn’t get out and how the fire started.”

Aniwhakaruru Sawers said the family were frustrated with Hart because he wasn’t making much sense.

“I just thought he was dumb and out of it.”

The trial, before Justice Geoffrey Venning and a jury, is now in its second week.