On May 29, 1994, Lyle Long Warrior was reported missing after he was last seen near the Missouri River by the railroad bridge in Pierre, South Dakota. Witnesses believed he may have fallen into the river, prompting an immediate and extensive search operation. Local law enforcement, search and rescue teams, and community volunteers conducted coordinated efforts, including underwater dives and ground searches along the riverbanks and surrounding terrain. Despite several days of intensive searching, no trace of Lyle was found, and his remains have never been recovered. His disappearance remains unresolved.