The Federal Bureau of Investigation on Tuesday announced that it was closing the books on a 1971 hijacking in which the culprit jumped from a stolen plane and made off with $200,000 in ransom money. After pursuing the case for decades, the FBI said its resources should be used to solve other crimes. “Evidence obtained during the course of the investigation will now be preserved for historical purposes at FBI headquarters in Washington, D.C.,” a statement released Tuesday read. The hijacking will now go down as one of the most remarkable crimes in U.S. history—and one that will remain unsolved. The hijacker, dubbed D.B. Cooper, claimed to have a bomb after boarding a Seattle-bound flight. He then demanded ransom money and that the plane fly to Mexico City after first letting passengers off in Seattle. But he vanished mid-air en route to Mexico, using a parachute to leap from the plane. His identity has never been determined, and it’s unclear if he survived the jump from the plane.