The Rooftop Theatre Shooting

At a rooftop theatre, a man came upon another man and shot him dead in front of a crowd. There is no dispute that he fired the shots. He believed the victim ran places where he ruined respectable young women by force or drugs. He also believed he had a special mission from Providence to stop him, and thought he was doing a good deed. He was charged with first-degree murder. His defence is insanity.