11/12/2014 02:47 EST | Updated 01/12/2015 05:59 EST

Tommy Gagné, convicted murderer, dies after being found unconscious in prison

A coroner is investigating the death of Tommy Gagné, the man sentenced to life in prison for the second-degree murder of Brigitte Serre.

Last Friday, Gagnée was found unconscious in his cell at the Macaza Institution, a medium-security facility located in the Laurentians.

He was taken to a nearby hospital in Rivière Rouge.

He died on Tuesday at the age of 28.

Gagné was convicted in 2007 and sentenced to life in prison for the death of 17-year-old Brigitte Serre.

Serre was stabbed to death in January 2006, while she worked alone during an overnight shift at a gas station in Montreal's St-Léonard neighbourhood.