Quebec provincial police were looking Friday for a convicted murderer who escaped from the province's main psychiatric hospital, the Philippe Pinel Institute in Montreal.

Krysztof Masiak, 48, was found guilty but not criminally responsible for killing his nine-year-old daughter, Natalie, in 2001.

She was found hacked to death in Masiak's apartment, where she had gone after a court granted him the right to see his daughter.

Her mother had full custody of the child.

Masiak was diagnosed as a paranoid-schizophrenic and admitted to the Pinel Institute in 2002.

He was out on day pass Thursday but did not return to the hospital at the end of the day.

The institute's director, Dr. Jocelyn Aubut, defended the decision to allow Masiak to leave.

He told CBC News that patients go through a rigorous evaluation before they leave the premises:

"Everyone is assessed by a multidisciplinary team," Aubut said, "We have a psychiatrist, psychologist, a criminologist. There are some special objectives tests which are passed.

"Every patient has to go before a tribunal before we give them day passes."

Police say Masiak has dirty blond hair in a brush cut, and was last seen wearing green military pants, a blue sweater and black boots. He was carrying a backpack.

Anyone with information on his whereabouts is asked to call the Sûreté du Québec.