TOUTLE, Wash. -

A Cowlitz County sheriff's officer says a 44-year-old dentist found lying next to an open vehicle at the Toutle River Rest Area on Interstate 5 in southwest Washington could not be revived.

Chief Criminal Deputy Charlie Rosenzweig says medics responded Wednesday evening after a 911 caller reported seeing the man. He was identified as William G. Lesh. The officer says Lesh had dental offices in both Olympia and Longview.

Rosenzweig says there were no signs of trauma. The Cowlitz County coroner plans an autopsy to determine the cause of death.

Sheriff's detectives are investigating.