(Radio Iowa) – Authorities investigating a fatal weekend plane crash in eastern Iowa have released the name of the man killed. Johnson County sheriff’s officials have identified the victim as 73-year-old Dale Bieber, of Coralville. They say Bieber was the only occupant of the single-engine aircraft that went down in a farm field near the Green Castle Airport northwest of Iowa City Sunday afternoon. Authorities say Bieber died at the scene.

Officials don’t yet know why the plane crashed. The cause is under investigation by the Federal Aviation Administration and National Transportation Safety Board.