David Livingston was serving a sentence for first-degree murder when he walked away from a farm annex of the Bowden prison. ((RCMP))

Police are searching for an inmate serving a sentence for first-degree murder who escaped from the Bowden Institution, 100 kilometres north of Calgary.

David Livingston, 61, "walked away" from the minimum-security farm annex Tuesday night between 7:30 and 10:30 p.m. MT, the RCMP said Wednesday. He is considered to be a "low public risk safety concern," they added.

Livingston was serving his time on a working farm and living in a house on the property that's adjacent to the Bowden prison.

The Innisfail RCMP conducted an immediate search of the area, but Livingston, who is originally from the Winnipeg area, could not be found.

He's described as five feet 10 inches tall, 161 pounds, with hazel eyes and thinning dark hair. He was wearing blue jeans and a green jacket.

Convicted of killing ex-girlfriend

Livingston was convicted of first-degree murder for shooting his ex-girlfriend, Eileen Marchinko, 33, in the forehead as she walked up to the front door of her home in March 1983.

He was distraught over unsuccessful attempts at reconciliation, according to the facts heard at his 1984 trial.

Livingston was sentenced to life in prison with no chance of parole for 25 years. After 23 years, he was granted unescorted passes to leave a minimum-security facility for no more than 72 hours a month, but was denied day parole.

Livingston was convicted of impaired driving while on conditional release in January 2007 and returned to custody, said Correctional Service of Canada.

He has been at the Bowden Institution since July 31.

Livingston made headlines in 2006 when he applied for an aboriginal parole hearing which includes a smudge ceremony and the attendance of an elder — despite being Caucasian.

He claimed to have embraced aboriginal cultural traditions, but the request infuriated his victim's sister, who told the Globe and Mail that the move reflected Livingston's manipulative qualities.