In a press release by the National Park Service, they announced the result of an autopsy on 67-year-old Mark O’Neill, whose body was found on the east shore of Shoshone Lake in Yellowstone National Park on Sept. 20.

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The autopsy determined the cause of death of O’Neill was exposure, or hypothermia.

O’Neill along with his brother, 74-year-old Kim Crumbo, were reported overdue by a family member from their four night backcountry trip to Shoshone Lake on Sept. 19.

The release states that search and recovery efforts continue at the lake to locate Crumbo, with crews from the National Park Service’s Submerged Resources Center using sonar equipment to help them find clues in the water.

Park crews continue to search for Crumbo by foot and boat, with assistance from Grand Teton National Park’s interagency helicopter, and dog teams from the Western Montana Search Dogs.

These recovery efforts will continue for the next several days as conditions warrant.

The incident remains under investigation, meaning the NPS cannot comment further about the specifics of the investigation, and will only provide updates when they deem it is appropriate to do so.

If you have information that could help investigators piece together a timeline of events, or if you were in the Shoshone Lake area between Sept. 12-19,  contact the NPS at 307-344-2428.

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