The hierarchical nature and brutal inner workings of a tough New Zealand jail block, including yard fights and sparring, has been examined at a prison murder trial.

The rare behind-bars glimpse came during the trial of three Christchurch Men's Prison inmates accused of murdering respected long-term prisoner Benton Marni Parata on March 25 last year.

Steven Betham, 36, Akuhatua Tihi, 22, from Toi Toi, Nelson, and Levi Hohepa Reuben, 21, deny murdering the fellow inmate.

Tihi today accepted he is guilty of manslaughter, but denied having murderous intent.
The Crown alleges that the trio had been acting to a pre-arranged plan in order to administer a serious beating.

The alleged assault came two days after 44-year-old Parata tipped off prison guards that Tihi had stolen a fellow inmate's prison-issue TV from his cell.

Corrections officers didn't think the incident - or 'tea-leaving', a prison term for thieving - was worth reporting.

Parata told the prison guards he would speak with the younger prisoners about showing respect to older prisoners or 'lags' doing longer stretches inside.

There was a "pecking order" in high-security Rawhiti unit, one prison guard accepted. Weapons, including shanks, were sometimes used in assaults.

The court heard how inmates refer to their cells as their 'house'. It's not uncommon for more junior prisoners to clean the cells of more senior lags, the court heard.

The "house proud" Parata was described as a tough stand-alone senior prisoner who held a certain mana. He was known to be tough, a prison guard accepted, and demanded that older men get respect from younger inmates.

Parata was a staunch stand-alone person, with no gang affiliation. He would talk to inmates regardless of their affiliations.

Asked by Reuben's defence counsel James Rapley if Parata was the type of guy who wouldn't back down, he replied: "I don't think he would, no."

Parata often stuck up for other prisoners - both older and younger - and one guard said he'd never seen him fighting.

"As prisoners go, he wasn't actually too bad a guy to deal with."

Rawhiti had a tough reputation as a "proving ground", the court heard.

"Just staying in there a while meant you're quite a tough person and can handle yourself," a Corrections officer said.

Inmates held unsanctioned fights or sparring bouts, which they called "training" in the exercise yard. Occasionally, they would wrap socks around their hands as gloves. 

Prison guards would break up the fights and use their discretion on whether inmates would face internal charges.

Inmates often have black eyes, cut lips, or bruising. Guards are often told the inmates "slipped in the shower" or "walked into a wall", the court heard.

On the day Parata was fatally-assaulted, the three accused men were seen on CCTV "loitering" near his cell during recreation time, the Crown alleges.

Parata walked into his cell at 9.22am. Tihi is alleged to have followed him in, with his hands bound in white tape, followed by Reuben and then Betham, the Crown alleges.

In a "little less than 90 seconds", Parata is battered around the head so badly, the Crown says, that he would die in hospital five days later.