A 1953 single-engine plane collided with a steep hillside in the Frank-Church Wilderness at dusk on June 26, killing pilot Neal Humphrey and his teenage son. The cause of the crash is still under investigation.

Federal investigators released documents this week outlining the circumstances of a fatal plane crash in the Frank Church Wilderness that claimed the lives of a former Hailey resident and his teenage son on June 26.

According to a press release from the Valley County Sheriff’s Office, 48-year-old Lewiston resident Neal Richard Humphrey was flying a single-engine, fixed-wing Piper PA-20 plane with his 16-year-old son, Cooper Layne Humphrey, as a passenger, when the plane crashed into a steep hillside around 8 p.m.

Humphrey and his son died of blunt-force trauma, Valley County Coroner Scott Carver ruled.