James G. Radakovich liked to dance with his wife at the local Serbian club and take care of his Cadillac and his yard, said those who knew him. No one knows what led to the shootings Saturday that claimed the life of Radakovich, his wife and their sons, both college students. Police say Radakovich shot them dead and then himself. ``You never know what goes on inside a family,'' said Richard Grilli, a neighbor. ``Something happened. He just cracked up,'' said Joseph Bergamasco, a police officer in this working-class Pittsburgh suburb. Mary Radakovich, 57, was found on the livingroom floor. One son, James L., 21, was in his bed, and Paul, 19, was on the floor of their bedroom. Radakovich, 54, a retired steelworker, died of a single gunshot wound in the head and was found beside his younger son, authorities said. He had two notes in a pocket of his pajamas, one a will, the other burial instructions. ``The note said he was sorry for what he is doing, but possibly they would all be better off wherever they were going. But it gave no reason,'' said Bergamasco. Investigators found no signs of struggle. ``Whether he was depressed, I don't know, but he didn't show it,'' said Samuel Budich, Mrs. Radakovich's brother. ``He was always a good husband to my sister,'' Budich said. ``Two weeks ago he was dancing the `colo' down at the Narodi Dom.'' The deaths were discovered after James' girlfriend alerted her father that all three family cars were parked at the home but no one was answering the door. Police found two .22-caliber pistols, a revolver and an automatic. Radakovich was laid off from the Homestead Works of USX Corp. two years ago, and had a good pension, relatives said. He caddied at the Oakmont Country Club for extra money. ``He took up golf when he was laid off,'' said Grilli. ``He'd have a beer now and then, but I never saw him drunk. He took care of his house and his lawn. He was nice, quiet.''