Case Details:Nicholas Jeffrey Mostert, 20, of Salt Lake City, Utah, was reported missing after an incident at Yellowstone National Park, Wyoming, on June 16, 2009. Mostert, a 2007 graduate of Skyline High School who was planning to attend the University of Utah, was observed by several witnesses at an observation platform along the rim of the Grand Canyon of the Yellowstone, near the brink of the Lower Falls. Witnesses reported that he jumped from the platform into the Yellowstone River and was carried over the 308-foot falls; park officials have characterized the incident as an apparent self-directed act. He was last seen wearing an olive green hooded sweatshirt and a white t-shirt. Park personnel recovered clothing believed to be his from an eddy approximately a quarter-mile downstream of the falls.

Yellowstone National Park rangers conducted a helicopter and ground search of the river corridor below the falls; Mostert was not located. No suspects, witnesses of investigative concern, or related persons of interest are documented in connection with the case, and no criminal investigation is open. The Wyoming Division of Criminal Investigation maintains the case in its statewide missing-persons repository; it is also listed with NamUs and the Doe Network (case #7079DMWY). Mostert is presumed to have drowned; his body has not been recovered and the case remains open. Anyone with information is asked to contact Yellowstone National Park at (307) 344-2640 or the Wyoming Division of Criminal Investigation. Case Number 091702.