NEW FAIRFIELD, Conn. -- A popular fifth-grade teacher fatally shot a masked, knife-wielding prowler outside his house during what appeared to be a late-night burglary attempt, only to discover he had killed his 15-year-old son, police say. Police said 15-year-old Tyler Giuliano was shot at about 1 a.m. Thursday in New Fairfield, a town just north of Danbury. The teacher's sister was alone in her house next door to his when she believed someone was breaking in. She called her brother, and he grabbed a gun and went outside to investigate, police said. The father confronted someone wearing a black...