The Regional Psychiatric Centre in Saskatoon issued a statement saying Traigo Ehkid Andretti was found unresponsive in his cell on Saturday and could not be revived.
Corrections officials will review the circumstances surrounding Andretti’s death and Saskatoon police and the coroner have been notified.
Andretti, 40, was convicted of first degree murder in 2014 for the death of his wife Jennifer McPherson.
Her remains were found scattered on a remote island off the east coast of Vancouver Island.
Andretti was subsequently charged with second degree murder in the 2006 slaying of Myrna Letandre in Manitoba, for which he later pleaded guilty.
Both murder charges carry automatic life sentences and the Manitoba judge overseeing court proceedings in the Letandre murders.
“You should be locked up for the rest of your natural life,” said Justice Chris Martin to Andretti as he formally passed sentence.
The Regional Psychiatric Centre is described by the Correctional Service as a multi-level security forensic psychiatry facility. It says inmates are housed in direct observation living units.