By Daniel DeMay;  January 4th, 2018;

A nine-digit number typed at the bottom of a letter believed to have been sent by the infamous hijacker confirms the note could have come from only one person, according to a cold-case investigative team.

That person is a San Diego man named Robert W. Rackstraw Sr., who served in the U.S. Army in Vietnam and is alive and well at 74. He may have put the code there to signal his co-conspirators that he survived a leap from a Boeing 727 over Southwest Washington, said sleuth Thomas J. Colbert.

But the letter – one of four copies mailed to newspapers in Los Angeles, Seattle, New York City and Washington, D.C., 17 days after the November 24, 1971 skyjacking – was immediately snapped up by the FBI, labeled as “evidence,” and filed away with the three others for almost five decades.

It didn’t see the light of day until Colbert and his partner-wife Dawna, organizers of the 40-member team, forced the FBI to give a copy up in a FOIA order last November.

Thomas Colbert believes two of Rackstraw’s escape partners are still alive. So now that the code-breaking is going national, “they’ll get his message with the rest of us.”

When Colbert released the Cooper letter to the media and his team, a former military code-breaker among his investigators noticed the numbers and, once another corresponding code was dug up from an L.A. Times archive, figured it all out.

The analyst claims the combined codes refer to three “masked” Army units that Rackstraw was connected to during his service. One of his former commanders told Colbert he would have learned the basic encryption before he was pulled from the unit because he didn’t qualify for security clearances.

Dorwin Schreuder, a former FBI agent who worked on the case in the early 1980s, said the codes are significant.

“I’m a hard skeptic, but I think the coding is remarkable,” Schreuder told SeattlePI. “Tom says nobody but Rackstraw would know these units and these figures, and if it’s true, that’s pretty hard to argue against. Rackstraw might be our guy.”

The FBI officially stopped pursuing the case in 2016, but said it would review any physical evidence of the parachutes or the money that turned up. It remains the only unsolved case of air piracy in the U.S.

Colbert’s team has amassed tons of research over seven years investigating the case, and the team’s efforts were featured in a 2016 History Channel documentary.

Last summer, his team brought the FBI several pieces of what they believed was a parachute strap and backpack from Cooper’s jump. The remote dig location, also turned over to the Bureau, came from a source who claimed to have heard the hijacker’s plan and escape from one of his old crime-partners.

That was four months ago, with not a word from the Bureau since.

Colbert said if the FBI doesn’t pursue the case further, his team will return to the dig site, knock on the door of the two elderly crime-partners, and continue looking for more evidence. He also believes the new Cooper letter and other clues indicate the Bureau is continuing to cover up that Rackstraw is a likely suspect.

Former FBI agent Schreuder has repeatedly complimented Colbert’s work, but also understands his frustration. The former G-man said in a recent email to the organizer that his work has absolutely moved the case forward.

“No one, yes I admit it, no one has come up with a more complete explanation and thorough documentation of this matter than you and your team,” Schreuder wrote in an email he shared with SeattlePI. “You seem to have gotten very near the finish line, while I and my [FBI] colleagues did not. Congratulations.”