A 31-year-old man will likely spend the rest of his life in a psychiatric institution for the killing of his parents in a Montreal suburb.

Mitchell Arnott has been found not criminally responsible for the double homicide and has been declared a high-risk accused, a designation reserved for those considered a serious threat to public safety.

In October 2022, he stabbed Wayne Arnott and Louise Boucher to death in their Île-Bizard home. He had been released from the psychiatric department at the Mon…