In 1971, an unidentified man known as D. B. Cooper hijacked a commercial aircraft in the United States, demanded $200,000 in ransom, and parachuted out of the plane mid-flight. He was never seen again. Despite one of the longest investigations in U.S. history by the Federal Bureau of Investigation, Cooper’s true identity, survival, and the fate of the ransom money remain unknown. The case was officially closed without resolution, making it one of the most famous unsolved crimes of the modern era.