Published: Oct 20, 2010 9:52 PM EDT
Updated: Oct 20, 2010 6:52 PM EDT

TAMPA, Fla. (AP) - An internal investigation determined that a Hillsborough County deputy ran a red light before a fatal crash with a semitrailer last month.

The sheriff's office reported Wednesday that 48-year-old Mark Longway was heading home from work in his cruiser Sept. 21 when he ran the light and hit the truck. He died at the scene.

The report says Longway was not talking on his cell phone or radio and was not using his computer at the time of the crash. Why the deputy ran the light remains unknown.

The driver of the truck was not injured.