According to a press release from Yellowstone National Park, officials located the body of a missing man along the east shore of Shoshone Lake in the park on Monday, Sept. 20.

Mark O’Neill, 67, from Chimacum, Washington, and his half-brother, Kim Crumbo, 74, from Ogden, Utah, were on a four-night backcountry camping trip and didn't return as scheduled. The pair was reported overdue by a family member on Sunday, Sept. 19.

A vacant campsite and gear were located on the south side of Shoshone Lake on Sunday. A canoe, paddle, lifejacket, and other items were found on the east side of the lake. During the morning of Monday, September 20, crews located the body of O’Neill along the east shore.

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Search & Rescue crews are still trying to locate Crumbo. The search will continue Tuesday with 10 crew members on foot in the area. Grand Teton National Park interagency ship and crew are also assisting with air operations.

Both O’Neill and Crumbo are National Park Service (NPS) retirees, and Crumbo is a former Navy Seal.

The incident remains under investigation, and officials say that they are unable to comment further about the specifics of the investigation. Updates will be provided when available. Law enforcement officials ask the public to give them space and avoid the area to protect the integrity of their work.

According to YNP, Shoshone Lake is the park’s second-largest lake. Its average year-round temperature is about 48 F (9 C). Survival time is estimated to be only 20 to 30 minutes in water of this temperature.

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