The apartment of a man allegedly killed on the orders of an underworld figure was entirely repainted, recarpeted and the locks changed around the time he went missing, according to a property manager.

The Crown contends Wang Baochang, known as Ricky Wang, was beaten up and stabbed to death in 2017, before his body was transported hundreds of kilometres, buried in an unmarked grave off the Desert Road and covered in concrete.

Zhao Jianqi and Gu Zhicheng, known as Michael, are charged with his murder.

Yu Gaoxiang, Piao Yanlong (Tony), Zhang Yuzhen have already pleaded guilty to helping hide the body, which laid untouched for two-and-a-half years until early 2020, after police received a tip-off to its whereabouts.

The Crown said Zhao, referred to as Uncle Six, Brother Six and Leo by his friends and associates, ordered Wang's death, after some pseudoephedrine went missing from their meth-making ring.

Wang lived in a Grafton apartment before his death. The property manager Cherie Lamb said his payments stopped in September, the month after Wang was allegedly murdered.

The property management company sent a 14-day breach notice seeking payment of the outstanding rent, and having received no reply, a 48-hour inspection notice, Lamb said.

When she went to investigate what was going on, she found the apartment empty.

"The light switches had all been taken off the walls, the venting had been taken down, I understand the property had been repainted and recarpeted too," Lamb said.

A locksmith had to get them inside because the external locks had been changed without their approval, she added.

Lamb said there were no personal items, just some rubbish, including dust or powder "of some sort".

She knew it had been repainted because there were buckets of paint around. It was news to her and the property owner, who had not approved the work.

Later testing revealed high levels of methamphetamine contamination in the apartment - "above safe habitation guidelines".

Later, another witness, Michael Gu's former girlfriend, said he had told her he was having trouble sleeping over this period.

"He's always sleepless because of his pressure at work," she said in court.

The woman said during their relationship Gu mentioned he was part of a gang with Brother Six - Zhao.

In its opening statement, the Crown said Zhao had ordered Wang to be killed after he thought Wang had either stolen or misplaced some of the pseudoephedrine they used to make methamphetamine.

The Crown alleged Gu took part in his death and used a large knife to cut Wang.

The defence refuted this, with counsel for both Zhao (Ron Mansfield QC) and Gu (Julie-Anne Kincade QC) arguing their clients had no involvement in Wang's death.

Both said the Crown case rested heavily on one witness, Tony Piao, who they said was a liar and unable to be relied on.

"What Mr Piao says about Mr Gu is a lie - it's a preposterous and outrageous lie. Mr Gu did not stab Ricky Wang or kill him in any way," Kincade said.

The trial, before Justice Lang and a jury, continues.

-RNZ.