EDMONTON - An Alberta man who killed a mother and her three children while driving drunk has died in an Edmonton prison.

The Correctional Service of Canada said Raymond Yellowknee, 37, died of an "apparent suicide" early Thursday while in custody at Edmonton Institution.

Yellowknee pleaded guilty in 2006 to four counts of impaired driving causing death as well as to criminal flight from police and driving while suspended.

He was drunk and driving a stolen pickup truck near Slave Lake, Alta., when he slammed into a car carrying Misty Chalifoux, 28, her daughters Trista, 9, and Larissa, 6, and her stepdaughter Michelle Lisk, 13.

Yellowknee, who had amassed a total of 71 offences and had been out of jail for only one year since he was 18, was declared a long-term offender in June 2008 and sentenced to 20 years in jail.

A coroner and police will investigate the death because he died in custody.