The man who attacked an investigator in downtown Calgary has been found not criminally responsible for his actions.

Lee Christopher Monrose was charged with attempted murder, aggravated assault and assault after he stabbed an investigator with the Alberta Serious Incident Response Team in June 2010.

Veteran RCMP officer Andy Johnson suffered serious stab wounds to his head, chest and thigh.

Monrose has been diagnosed with paranoid schizophrenia and a Calgary judge ruled Monday that he was incapable at the time of the attack of understanding right and wrong.

His victim accepted the verdict.

"I believed he was mentally ill and a couple of times I dealt with him I thought there were some mental illness issues with him," said Johnson. "Of course I didn't know that he would be dangerous to that extent."

Monrose will remain in custody and faces a psychiatric review to determine his future.