Christopher Lane, who was visiting the town of Duncan where his girlfriend and her family live, had passed a home where the boys were staying and that apparently led to him being gunned down at random, Police Chief Danny Ford said Monday.
A 17-year-old in the group has given a detailed confession to police, but investigators haven't found the weapon used in last week's shooting, Ford said.
That teen and the others - ages 15 and 16 - remain in custody, and Ford said the district attorney is expected to file first-degree murder charges Tuesday. It wasn't known if the three will be charged as adults or juveniles. They are scheduled to appear in court Tuesday afternoon.
"They saw Christopher go by, and one of them said: 'There's our target,'" Ford said. "The boy who has talked to us said, 'We were bored and didn't have anything to do, so we decided to kill somebody.'"
He said they followed the 22-year-old Lane, a student from Melbourne attending college on a baseball scholarship, in a car and shot him in the back before driving off.
Ford told the television station KOCO in Oklahoma City that one of the teens said they shot Lane for "the fun of it."
