A convicted killer, who has escaped lawful custody before, has gone missing from the Mission Institution minimum-security prison in the Lower Mainland this long weekend.  He is the second convicted murderer in a month to escape from the facility.

Michael Douglas Sheets, 48, was not accounted for during a routine count of inmates Saturday at 7 p.m.  The RCMP has issued a warrant for his arrest.

Sheets is serving a 14-year sentence for manslaughter, after firebombing a Calgary townhouse in 2004, killing a young brother and sister and injuring their mother.  He was also found guilty of escaping lawful custody from William Head Institution on Vancouver Island in February 2015.

Another inmate, John Norman Mackenzie, also escaped the same Mission, B.C. prison in early August. Mackenzie was serving a life sentence for second-degree murder.

Sheets is five-foot-six in height and weighs 141 pounds. He has a fair complexion, hazel eyes and brown hair. He may also be using the name John Hala. Corrections Services Canada is investigating the circumstances of his escape.

Anyone with information on the whereabouts of Sheets is asked to contact police.