- The D.B. Cooper manhunt has been one of the longest investigations in FBI history
- In order to solve a case, the FBI must prove culpability beyond a reasonable doubt
(CNN)The last time anyone saw D.B. Cooper, he parachuted out of a Mexico City-bound airplane with $200,000 in ransom strapped to his body, vanishing over the Pacific Northwest and initiating one of America's greatest manhunts.