By Laura Zuckerman
May 19 (Reuters) - A Montana teenager fatally shot his 15-year-old friend after mistaking him for an intruder when the boy threw a rock at his bedroom window in the predawn hours and then stuck his head through it, police said on Tuesday.
A preliminary probe into the shooting found the teen was sleeping in the family's Billings home just before 2:30 a.m. on Sunday when his friend Mackeon Schulte and another teenage boy sought to rouse him but instead sparked fears of a break-in, said Billings Police Department Captain John Bedford.
The teen grabbed a revolver, a family heirloom he kept in his bedroom, and shot Schulte in the head in an incident Bedford described as a "horrible tragedy." Schulte died a short time after being taken to a hospital, police said.
Bedford said investigators believed the teenager, whose name was withheld, did not intend to kill his friend, but that the county prosecutor would ultimately decide whether any charges would be brought against him.
The third teen was uninjured, Bedford said.
Fellow students, educators and staff at Billings Senior High School have been offered professional counseling sessions in the aftermath of the shooting, said Billings schools chief Terry Bouck.
"We're shocked by this tragic death. We've worked hard over the past two days to help support our students and community. We're doing the best we can to deal with this terrible situation," Bouck said on Tuesday.
Bedford said police expected to submit findings from their probe to the local prosecutor as soon as Friday. (Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Cynthia Johnston and Peter Cooney)