PORTLAND – A Standish man was found not criminally responsible by reason of insanity Tuesday for stabbing his father to death.

Kristian McKay fatally stabbed his father, Donald McKay, in a sudden knife attack in their Standish home last March. He was 21 at the time, and the attack came without warning or provocation.

At the time, McKay’s parents thought he was on the road to recovery after suffering a pair of mental breakdowns.

In Tuesday’s court ruling, McKay was committed to the Riverview Psychiatric Center in Augusta. He’s been at the hospital since May, when a judge ordered him there for observation and treatment.

Psychiatrists testified that McKay suffers from schizoaffective disorder and could not appreciate the wrongfulness of his actions.

While in high school, McKay was a good student and athlete. But he began exhibiting signs of mental illness during his freshman year at the University of New Hampshire.

His attorney, Robert LeBrasseur, said McKay’s mother, Cathleen McKay, was devastated by her husband’s death but maintained steadfast support for her son through the proceedings, visiting him almost every day. She recently died of cancer and did not see her son’s court case resolved, LeBrasseur said.