Cracked: The codes that private investigators say prove D.B. Cooper's identity as Army veteran

It wasn't long ago that filmmaker, author and self-styled D.B. Cooper sleuth Tom Colbert released his latest find: A sixth letter from the famed hijacker that reportedly contained a coded confession.

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A member of Colbert's cold case team -- comprised of 40 former law enforcement and military personnel -- was retired U.S. Army code breaker, Rick Sherwood, and when he saw the alleged fifth letter sent by Cooper to newspapers, he wondered if the odd numbers in it could be a code.

The sixth letter allegedly sent by D.B. Cooper, with the coded messages found by Rick Sherwood, a retired U.S. Army codebreaker and part of Tom Colbert's investigative team that tracked the case for seven years.
Courtesy Tom Colbert

Sherwood spent two weeks with that letter, eventually coming up with a translation of the odd numbers to old Army units -- three units, to be specific -- that happened to also be the three units of a man Colbert believes to be the real Cooper.

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Then Colbert got another letter back -- the sixth letter -- in the FBI's response to longstanding public records requests. In that letter, Sherwood decoded what he and Colbert said is a confession.

"I'm Lt. Robert Rackstraw," read one part of the coded message, according to Colbert and Sherwood. Rackstraw, a retired U.S. Army Vietnam veteran, was considered and then dismissed as a Cooper suspect by the FBI in the late 1970s, but Colbert and his team's investigation says otherwise.

The mystery of D.B. Cooper

The mystery began on Nov. 24, 1971 when a man calling himself Dan Cooper bought a one-way ticket on Northwest Orient Airlines from Portland to Seattle. Once aboard the Boeing 727, he slipped a note to the flight attendant saying he had a bomb and that he wanted $200,000 and four parachutes, as well as a refueling truck ready when they landed in Seattle.

In Seattle, the man exchanged the passengers for the ransom money and the plane took off, headed for Mexico. Somewhere over southwest Washington, Cooper jumped out the rear stair door of the plane and was never heard from again. The only verifiable evidence ever found was a small cache of $20 bills found near the Columbia River in 1980.

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.

In 2016, Colbert's team of former law enforcement officers, including retired FBI agents, used a lead about where Cooper landed to track down some bits of fabric they believed to be part of the parachute. They handed those over to the FBI and and haven't heard back since.

That story, relayed by an old pilot named Wally to another pilot, told of three accomplices using a small plane and a ground vehicle to pick Cooper up after his jump and then help him escape. The four had plotted and practiced in advance, the story goes.

But there's much, much more. Colbert said his team found old officers who served with Rackstraw in the military who said he was involved in secret units and even the CIA, a reason Colbert gives for him being let off the hook even after FBI questioning in 1979.

Another part of the narrative has Cooper tossing $50,000 of his ransom money into Vancouver Lake as part of an elaborate scheme to suggest he died in the jump. But the money didn't wash up as planned, so a second effort planted the money at the Columbia River beach where it was found in 1980.

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"We know it's Rackstraw," Colbert previously told SeattlePI. Pointing to the unit names allegedly coded into the fifth letter, he said there could be little doubt. "He was the only man in the whole American army with those three units."

On Wednesday, Colbert released the details of how Sherwood decoded the messages.

The code itself is relatively simple. A number is assigned to each letter of the alphabet in order (A=1, B=2, etc.). But it's not a only matter of spelling words out with numbers. Instead, the values are added up and then decoded by finding other words that add up to the same value.

For example, "D.B. Cooper" tallies up to 78. One could decode that to read "A wrong."

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Digital photograph showing an artist conceptual sketch of "Dan Cooper" aka DB Cooper, who hijacked Northwest Orient Airlines flight 305 on November 24, 1971. Black and white drawing shows a white male with short hair, wearing a suit and necktie.FBI/Courtesy of the Washington State Historical Society

(L to R) Captain William Scott; First officer/copilot Robert Rataczak; flight attendant Tina Mucklow; and second officer Harold Anderson are shown here at a news conference in Reno, Nevada, after the arrival of Flight 305 to Reno International Airport. Two other members of the flight crew not pictured - Senior flight attendant Alice Hancock and flight attendant Florence Schaffner - had been released along with the 36 passengers earlier in Seattle. Photo date: November 25, 1971.Seattlepi.com photo/Courtesy of the Washington State Historical Society

This digital photograph shows a two-piece orange and green flight suit and helmet from an F-106 aircrewman of the 318 FIS, McChord AFB, ca. 1971. Two F-106 "Delta Dart" aircraft pilots from the 318 FIS at McChord Air Force Base followed Flight 305 from Seattle after it left for Mexico City. Neither pursuit aircraft observed Cooper making his skydiving escape via parachute from Boeing 727 aircraft.McChord Air Museum Foundation/Courtesy of the Washington State Historical Society

FBI Agent Dick Dyer of Vancouver, Wash., left, and Sheriff Gene Cotton of Clark County examine a pair of pants found in a tree about 25 feet off the ground in southwest Washington. The pants were thought to have belongd to D.B. Cooper, the only successful parachute skyjacker. The pants, photographed here Nov. 25, 1976, were not Cooper's. The hijacker has never been found. (The Associated Press/provided by seattlepi.com file)P-I File

The artifact shown is a military-style, backpack type parachute with a �quick fit� harness, manufactured by the Pioneer Parachute Company, Inc., in 1957. This was one of four parachutes provided to Northwest Orient Airlines, as part of the ransom demands made by Dan Cooper, AKA �DB Cooper,� during his hijacking of Northwest Orient Airlines Flight 305 on November 24, 1971. All four parachutes were loaded aboard the Boeing 727 commercial aircraft at Seattle Tacoma International Airport, along with $200,000 in ransom money. The parachute was obtained for the Washington State Historical Society�s permanent collection in 2013, for display as part of the exhibition COOPER at the Washington State History Museum, in Tacoma, WA, from August 24, 2013 through January 5, 2014.Pioneer Parachute Company, Inc./Courtesy of the Washington State Historical Society

Digital photograph of a metal identification panel, for a Boeing 727-051 aircraft identified as manufacturers serial number 18803. View of panel taken at an angle.This aircraft was the Boeing 727 aircraft used by Northwest Orient Airlines as flight 305, on the day of the DB Cooper hijacking on November 24, 1971. The aircraft was first delivered on April 22, 1965 and registered as N467US with the FAA. Plate is oblong with four holes in the corners for mounting. The plate was removed from the aircraft at the time it was scrapped in 1993.Photo by Tom Collins of Renton, Wash./Courtesy of the Washington State Historical Society

Digital photograph showing group of federal agents, representatives from Northwest Orient Airlines, and military personnel from McChord AFB in group photograph at rear of the Boeing 727 aircraft hijacked by DB Cooper. Orginal photo taken at Seattle-Tacoma International Airport, on January 6, 1972. On this date, a flight test originated from the airfield to recreate the jump from a 727 in flight made by Dan Cooper, aka DB Cooper, on Nov. 24, 1971.FBI Special Agent John Detlor/Courtesy of the Washington State Historical Society

Numbers can also be added up along with the values from letters, as Sherwood did with the combos of letters and numbers in the fifth letter.

Coded messages in the six letters allegedly sent by Cooper to newspapers included statements that indicated he was a CIA operative, that he was trained by the U.S. government, the statement that he was Rackstraw and more, according to Colbert.

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The simplicity of the code meant that one could come up with any number of different messages out of the text decoded by Sherwood, but understanding the context and the language of the era helped guide him, he told Colbert.

Sherwood had previously put together a collection of words and language used in the late 1960s among Vietnam-serving military personnel. That, along with other aspects of the letters, including indications in the sixth that Cooper was trying to tell who he was or wasn't, helped him determine what he might uncover, Colbert said.

"So he (Sherwood) was looking for a reveal," Colbert said. "So that put him in the mind of who he was looking for."

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Who he found was Rackstraw, a man who hasn't made a clear denial of the claim, but who also hasn't been revisited as a suspect by the FBI. The FBI officially stopped pursuing the case in 2016, saying it would only return to it if physical evidence of either the money or the parachute turned up again.

In 2017, Rackstraw told SeattlePI that its reporter should verify Colbert's claims, but didn't deny anything outright. At the time, he expressed frustration with Colbert's pursuits.

The codes may mark the end of Colbert's constant pursuit of the case, he said. He has been following the case for seven years, amassing a case that at least on its face appears more in-depth and credible than most of the dozens of other amateur theories on what became of the hijacker.

Last year, Colbert and his team followed tips to a remote location in the Cascade foothills to dig up pieces of fabric that they said were part of Cooper's parachute. They turned over the evidence and the location to the FBI, but haven't heard anything further since.

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The story that led them there came secondhand from an old pilot who claimed to have been one of several men involved in helping Cooper in an escape that involved throwing $50,000 out of an airplane and later orchestrating a find of some money along the Columbia River. Add to that Colbert's claims that Cooper was CIA and that the FBI has worked actively to cover up evidence since the late 1970s, and the story becomes even more incredible than the few facts that are known and provable.

The FBI, for its part, has only repeated its statement that it will pursue physical evidence.

Colbert also worked with the History channel to produce a documentary on the case that came out in 2016, and it seems likely another film on the topic may be in the cards.

For now, Colbert is convinced he's found the genuine Cooper, but the internet is full of Cooperites (the nickname for followers and theorists of the case) who say otherwise.

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The mystery of the polite man who hijacked an airliner and got away with it will remain just that for now: A mystery.

Senior editor Daniel DeMay can be reached at 206-448-8362 or danieldemay@seattlepi.com. Follow him on Twitter: @Daniel_DeMay.