Authorities investigating a fatal 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 said Bieber was the only occupant of the single-engine aircraft that went down northwest of Iowa City on Sunday.

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

Johnson County sheriff's officials said they received several 911 calls from witnesses who reported seeing the small plane crash in a farm field near the Green Castle airport near Oxford just before 4 PM. Multiple agencies responded.

Authorities said Bieber died at the scene.

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