Murder-accused David Benbow learnt to restrain people, crime scene preservation during time as Corrections officer, court hears

Murder-accused David Benbow's training as a Corrections officer taught him to restrain and subdue people, the jury at the High Court in Christchurch heard on Thursday.

Benbow trained with the Department of Corrections in the months before his childhood friend Michael McGrath went missing, where he also learnt about the preservation of a crime scene.

Benbow is now flanked by prison officers but six years ago, he was a prison officer himself.

He had had a career change and joined the Department of Corrections the year before the Crown alleges he murdered McGrath.

Benbow is accused of luring McGrath to his house to help him move some railway sleepers, but instead he allegedly killed him.

A Corrections principal advisor explained to the jury what Benbow had been trained in, in the months before McGrath went missing.

"Part of the control and restraint training involves teaching how to physically control and restrain a prisoner using a variety of hand-to-hand control methods," Department of Corrections principal adviser Simon Edhouse said.

Benbow learnt effective ways to subdue and suppress another adult.

"Whereby Corrections officers can apply pressure to a prisoner's arm or wrist using specific techniques to immobilise them," Edhouse said.

The court heard when Benbow was working at Christchurch Men's Prison, he saw a fellow Corrections officer enter a cell only to be punched by the prisoner inside. Benbow went to help by restraining the prisoner's legs to stop him kicking out.

"So what we know is that the only time he got to put his training into place, he helped hold somebody's legs then exited as soon as more qualified staff came on?" defence lawyer Kathy Basire asked.

"That's what I understand, yes," Edhouse replied.

Benbow was also trained in crime scene preservation.

"They are taught not to touch, remove or clean anything to secure and preserve the scene and any potential evidence," Edhouse said.

Skills the murder-accused learnt in his training and is now hearing about on a daily basis in court.