An investigation is underway into the death of an inmate at Collins Bay Institution in Kingston.
Correctional Service of Canada officials say 50-year-old Jeffrey Glen Kellar died in custody on Thursday.
No other details were released, but Acting Assistant Warden Chris Staley says a lockdown has been put in place so staff can conduct a search of the facility and visits have been suspended for the time being.
Kellar was serving a 12 year sentence for manslaughter.
A newspaper report in the Edmonton Journal says Kellar had pleaded guilty in 2009 after his wife was killed during an incident in Edmonton in 2007.