RIVERTON, Wyo. (AP) — Authorities say a 33-year-old man found dead in the mountains in Fremont County likely died of hypothermia.

Fremont County Coroner Ed McAuslan says Blaine Thomas Revere, of Fort Washakie, was found in the last Saturday morning.

The FBI handled the investigation into the death because it occurred on the Wind River Indian Reservation where Revere and two friends were four-wheeling when the vehicle broke down.

McAuslan says the trio tried to find help with Revere and another walking one way and the third man walking a different direction.

He tells the Riverton Ranger that at one point, Revere fell and his friend could not get him up.

The friend went on to a residence where he called for help.

The FBI has been determined the death to be accidental.