NEW HAVEN, Conn. (AP) — A popular teacher who fatally shot a knife-wielding prowler in a ski mask and then learned it was his 15-year-old son is devastated and filled with questions about what the boy was doing, his attorney said Monday.

Jeffrey Giuliano went outside with a gun around 1 a.m. Thursday when his sister called to say someone was trying to break into her house next door in New Fairfield, a town of nearly 14,000 people about 50 miles from New York city. Giuliano saw a masked person holding a weapon come toward him in a threatening manner and shot him, state police said. He learned later the person he killed was his son Tyler Giuliano.