Updated with further information:

Dworshak worker's cause of death ruled carbon monoxide poisoning

Clearwater County Sheriff's Office Tuesday released information on the autopsy and toxicology of Eric Engle, 54, Orofino, a U.S. Army Corps of Engineers employee who was found deceased in the area of the powerhouse early June 30.

Following an autopsy ordered by the Clearwater County Coroner, CCSO reported that Engle died due to carbon monoxide poisoning from inhalation of exhaust fumes. Engle had been operating a gas-powered washer in a small access leading to the diversion tunnel.

A Corps spokesperson in their Walla Walla, WA, district office said they are conducting their own internal investigation into the death and would not have any further comment until that is completed.

"We can confirm OSHA's Boise Area Office is conducting an investigation. However, please note that because this is currently an open case we cannot provide further information or details at this time," said Jose A. Carnevali Deputy Regional Director for Public Affairs, Department of Labor - San Francisco Office, in an email.