In 2016, the FBI officially closed its investigation into the identity of airplane hijacker D.B. Cooper. The man who called himself D.B. Cooper hijacked an American airplane in 1971. The FBI investigated more than 100 persons of interest but was never able to determine the identity of D.B. Cooper. After a 45-year investigation, the FBI was forced to close the case. The bureau had no solid evidence or leads, and it needed to devote more resources to new cases.