WASHINGTON (CN) - Six months ago, Thomas Colbert ended a seven-year private investigation of D.B. Cooper - the now infamous skyjacker who disappeared after parachuting out of a commercial airliner in 1971 with a $200,000 ransom.
Confident he has definitively unmasked Cooper's true identity, Colbert now wants to explain how his team members decrypted hidden messages they believe the hijacker embedded in letters sent to several newspapers in the days, weeks and months following the hijacking.
There are six messages in all, and the FBI turned them over to Colbert’s team following successful litigation under the Freedom of Information Act.
Mark Zaid, a national-security attorney working on the investigation, said in an interview that they found the most damning piece of evidence in the sixth and final letter to come to light.
Mailed from Florida on March 28, 1972, the letter says the hijacker is alive and has just returned from a trip to the Bahamas.
"So your silly troopers up there can stop looking for me,” it states. “This is just how dumb this government is. I like your articles about me but you can stop them now. D.B. Cooper is not real."
But a code breaker on Colbert and Zaid’s team said their decryption efforts on the sixth letter unearthed an embedded confession: "I'm LT Robert W. Rackstraw."
"It specifically identifies by name the very person we have been stating all along is the true hijacker," Zaid said in a phone interview. "And he remains alive and well in the San Diego area, and we're all waiting for the FBI to make the next move."
Rackstraw, a 74-year-old former U.S. paratrooper still living in southern California, refused to be interviewed for this article. The Vietnam War veteran has long denied in press reports, however, that he is the man who hijacked Northwest Orient Flight 305 on Nov. 24, 1971.
Last year, in a friend of the court brief he filed in Colbert’s FOIA case, Rackstraw accused the investigators of ruining his life.
The FBI did have Rackstraw on their radar in the early 1970s, but later cleared him. Colbert, a producer who wrote a book about Cooper called “The Last Master Outlaw,” believes this decision was negligent.
Secret Messages Decoded?
To decode the Cooper letters, Colbert recruited another Vietnam veteran named Rick Sherwood. During the war, Rackstraw briefly served as a chopper pilot in the same unit as Sherwood: the Army Security Agency's signal-tracing chopper program called Project Left Bank.
That's where Sherwood learned the alphabet-numeric coding, which he describes as two years of college jam-packed into 16 weeks of training. Rackstraw, whom he says he did not know personally, would have learned it there, too, and Sherwood believes he used it to encrypt messages in the six letters.
The code transforms letters into numbers and vice versa, where A=1 and B=2, etc. So the word sun, for example, would equal 54 when the numeric values for each individual letter of the word are added up (S=19; U=21; N=14).
But Sherwood says anyone trying to decode an encrypted message would need to know something about the person who wrote it.