One of the country's most brutal and high profile killers has been moved into an at-risk unit and will be constantly monitored for the foreeable future following an incident at Auckland Prison involving an "improvised weapon".

George Charlie Baker, jailed for life for the murder of teenager Liam Ashley in the back of a prison van in 2006, was moved to the at risk unit at the maximum security prison after an incident on Friday.

The Herald understands Baker was caught with a shank - a homemade weapon.

A source said it appeared to be made from a piece of metal aerial with one end sharpened.


Baker was moved to the at-risk unit soon after.

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Prison director Tom Sherlock said no staff or prisoners were injured during the incident, but would not be drawn on the specific details.

"Violence against staff and other prisoners and possession of weapons, including shanks, are not tolerated in New Zealand prisons," he said.

"If an offender is found in possession of a weapon or using violence they will be held to account."

Sherlock refused to say whether Baker would face charges in relation to the incident, or where the shank may have come from.

Baker has a history of using improvised weapons against prison staff and other inmates.

He has also self-harmed in the past.

"This prisoner's management and security classification are reviewed regularly," Sherlock told the Herald.

"At risk units accommodate prisoners who have been assessed as potentially suicidal or wanting to self-harm.

"These cells have limited fixtures and fittings and have been designed to reduce the ability to self-harm. The cells are under 24-hour camera observation. Special clothing and bedding is also provided to minimise opportunities to self-harm.

"Prisoners in these situations are monitored according to their management plan requirements."

The incident occurred just days before the 10th anniversary of Ashley's murder.

On 24 August 2006 Baker and Ashley, 17, were being transported from court to Mount Eden Prison in a prison van.

Baker attacked Ashley, strangling him then stomping repeatedly on the teenager's head as the van travelled across Auckland.

When Corrections staff opened the van to let the prisoners out at Mount Eden they found Ashley lying on the floor.

"You better get him out of there. I've just killed him. He's not breathing," Baker told them.

Ashley died the next morning after his family withdrew life support.

In November 2006 Baker was sentenced to life in prison, with a minimum non-parole period of 18 years.

In 2010 he was convicted of attacking guard as he was being transported back to Paremoremo from Middlemore Hospital, where he had been treated for a self-inflicted wrist would.

In August that year he was convicted of taking an 82-year-old fellow inmate - a child sex offender - hostage and threatening to kill him.

In both attacks Baker used makeshift weapons.

In August last year he made headlines again after telling other inmates he was having a sexual relationship with a female guard, whose name he got tattooed across his chest.

Prison director Tom Sherlock confirmed there was "no truth" to the allegations and Baker was simply "infatuated" with her.