Owyhee County officials found and removed a truck that was submerged in the water at a boat ramp at Cottonwood Campground Thursday evening.
Inside the truck, they found the body of 67-year-old Russell Holsinger of Mountain Home, who was reported missing on April 12.
Detectives are investigating the cause of death.
The Owyhee County Coroner said Thursday that he wasn't able to determine Holsinger's cause of death. A toxicology report has been issued, which could take six to eight weeks.
Anyone who may have seen Holsinger or had contact with him in Owyhee County or at the campground is asked to call the Elmore County Sheriff's Office at 587-2100.