A state police spokesman, Lt. J. Paul Vance, said the teen had never been in trouble with the law, and some of those who knew him described him as a good kid with an easygoing personality. Investigators and acquaintances said they were at a loss to explain what he was doing outside dressed all in black and carrying a weapon.
State police said the shooting happened after Jeffrey Giuliano got a call from his sister next door saying that someone might be trying to break into her home in their neighborhood of colonial-style houses. Giuliano grabbed a handgun and went out to investigate, troopers said.
He confronted someone in a ski mask and opened fire when the person came at him with something shiny in his hand, police said.
When police officers arrived, Tyler was lying dead in the driveway with a knife in his hand, and his father was sitting on the grass. Detectives informed Giuliano several hours later that he had shot his son, Vance said.
Police were investigating whether the father's gun was registered.
Tyler was a student at New Fairfield High School and a Civil Air Patrol cadet. Some of those who knew him said he enjoyed spending time with his family and flying gliders and small planes. He was adopted by Giuliano and his wife a few years ago, friends said.
One classmate said many students couldn't make sense of what happened.
"He just wasn't the type to do what happened," said Erin Pallas, 16. "So it didn't make sense to us."