Mountain Institution is a medium-security facility located in the upper Fraser Valley near the community of Agassiz British Columbia, approximately 140 kilometres east of Vancouver. (Parole Board of Canada)

RCMP have charged a convicted serial killer with the first-degree murder of his cellmate at a Fraser Valley correctional institution last November.

Authorities at Mountain Institution, located in the Fraser Valley east of Vancouver, found Jeremy Phillips, 33, dead in the cell he shared with Michael Wayne McGray.

According to a warrant used to search the cell, the convicted serial killer admitted to murdering his cellmate minutes after authorities discovered the body.

The warrant said Phillips appeared to have been beaten with a cat scratch post. McGray said he used a bed sheet as a ligature and later flushed it down the toilet, but gave no motive for the alleged murder.

RCMP Cpl Dale Carr said there was no need to rush charges in the investigation.

"There was no concern for public safety. Mr McGray was in custody. He's going to remain in custody for the balance of his life," said Carr.

Urge to kill not controlled by prison

Phillips, who was from Moncton, N.B., had reportedly asked to be moved from the cell he shared with McGray because of his own concerns for his safety.

Phillips was serving time for aggravated assault while McGray is serving six concurrent life sentences for murder.

A decade earlier McGray told the media he'd killed 16 people, although he was only convicted in six cases. In a CBC News interview, he talked about his urge to kill, and what he would do, even inside a prison.

"It's like a craving or hunger... It's something I have to do... It gets to a point where I just can't control it anymore," he said.

"I want to go to an institution, a hospital somewhere for a while where I can get some treatment because if I don't, just because I'm in prison doesn't mean the killing's going to stop," he said.