The body of a Washington state man was found Monday along the east shore of Shoshone Lake in Yellowstone National Park.
Park crews on Monday found the body of Mark O’Neill, 67, of Chimacum, Washington, on the east shore of the lake.
O’Neill and his half-brother, Kim Crumbo, 74, of Ogden, Utah, were reported overdue from a four-night backcountry trip to Shoshone Lake by a family member on Sunday.
On Sunday, park crews located a vacant campsite and gear on the south side of the lake, as well as a canoe, paddle, personal floatation devices and other personal belongings on the east shore of the lake.
Search and rescue efforts continued Tuesday, with 10 crew members searching for Crumbo on foot.
A Grand Teton National Park interagency ship and crew are also assisting with air operations.
Both O’Neill and Crumbo are National Park Service retirees, and Crumbo is a former Navy Seal.
The incident remains under investigation.
Shoshone Lake, the park’s second-largest lake, is located at the head of the Lewis River southwest of West Thumb. At 8,050 acres, its average year-round temperature is about 48 degrees. Survival time in the cold water is estimated to be only 20 to 30 minutes.