An intriguing twist in the DB Cooper hijacking case: Amateur investigators say a 1971 letter believed to have been sent to authorities by the hijacker has a code that points to his identity, reports Oregon Live. The sleuths, who are preparing a documentary, say they've deciphered a series of numbers at the bottom of the letter that prove a Vietnam vet named Robert Rackstraw of San Diego is the famous bandit. They're not providing precise details on how they arrived at the conclusion just yet, but they say the numbers, including 717171634, refer to Army units that Rackstraw served in during the war, reports the Seattle Post-Intelligencer. A former military code-breaker on the investigative team, led by documentary filmmaker Tom Colbert, is behind the apparent discovery.
Rackstraw's name has surfaced before as a suspect, and he's been coy of late on the subject. "They say that I’m him," the 73-year-old told the San Jose Mercury News last year. "If you want to believe it, believe it." Last summer, the FBI formally closed its investigation into the hijacking, in which the man dubbed Cooper parachuted out of a plane over Washington state with $200,000 in cash. Rackstraw is a former Army paratrooper, one of the many reasons Colbert's team has long focused on him. In the 1971 letter, the hijacker says he used face putty to disguise himself, which could explain why Rackstraw, who was in his 20s at the time, could have resembled the middle-aged hijacker depicted in the famous artist's sketch of Cooper.