Douglas Garland — recently convicted of murdering a Calgary boy and his grandparents — is in hospital again after being beaten by inmates for the second time in three weeks, CBC News has learned.

The assault took place at the Edmonton Institution, just hours after Garland was transferred to the maximum security prison from the Calgary Remand Centre.

After the beating, Garland was found unconscious in his cell, sources told CBC News.

Garland is in stable condition and was kept in hospital overnight as a precaution, said his lawyer Kim Ross.

Alberta Health Services confirmed paramedics transported a patient from the Edmonton Institution to a nearby hospital in stable condition on Monday night just after 9:00 p.m.

"I'm very upset," said Ross.

"I can tell you if this is a situation where this has been allowed to happen, I anticipate there will be legal actions that will be taken."

Edmonton police and the Correctional Service of Canada are conducting their own investigations, said Matt James, assistant warden at the Edmonton Institution.

"​The safety and security of institutions, their staff and the public remains the highest priority in the operations of the federal correctional system," said James in a written statement issued on Tuesday.

The prison was aware of Garland's history of being assaulted at the Calgary Remand Centre. Garland was assessed for placement before being housed in one of the Edmonton prison's quietest units, which doesn't generally have problems, Ross says he was told by corrections officials.

Garland, 57, was sentenced to life in prison in February with no chance of parole for at least 75 years for the first-degree murders of Alvin and Kathy Liknes and their five-year-old grandson Nathan O'Brien.

Prosecutors had argued during the trial that the three family members were taken from the Liknes's home alive on June 29, 2014, then killed on a farm near Airdrie, north of Calgary, where Garland lived with his parents.

Garland hospitalized after sentencing

The Crown's theory was that Garland burned the bodies.

During the trial, jurors heard evidence Garland was motivated by a grudge over a business relationship with Alvin Liknes that had soured years before.

The boy happened to be at his grandparents' home for an impromptu sleepover the night Garland executed his plan to kill the Likneses.

Just hours after he was sentenced, on Feb. 16, Garland was attacked at the Calgary Remand Centre by four inmates.

He was taken to hospital with soft tissue injuries.

Ross said the correctional officers in Edmonton should have known Garland requires special handling to ensure his safety.

"I don't know the circumstances, but in my view it doesn't really matter," said Ross.