Authorities say a father and son found a dead body while fishing north of Lincoln on Wednesday afternoon.
The man's body does not show an obvious cause of death, officials said. He has yet to be identified. The body was found in Landers Fork Creek about a mile north of Copper Creek Road.
"There is nothing so far to explain to us the why, how or what," Lewis and Clark County Coroner Bryan Backeberg said Wednesday night. "The circumstances are pending."
Backeberg was transporting the body to the State Crime Lab in Missoula for an autopsy.
Lewis and Clark County Sheriff Leo Dutton said the man was found in a remote area that was not easily accessible. A search-and-rescue crew extracted the body from the scene.
"The details are sketchy," Dutton said.
It appears the body had not been there very long, he added.
"It's a John Doe at this point," Dutton said.
The man is believed to be about 30 or 40 years old. He was wearing only shorts when he was found. Backeberg said although the man was located in the water, it is not known if he was swimming at the time of his death.
One of the only clues found near the body was a stolen car. Dutton said a car stolen on July 31 was located about eight miles from the body. Investigators believe the two are linked.
Authorities said more details will be released Thursday.