Investigators claim they have finally confirmed the identity of DB Cooper, the infamous 1971 airplane hijacker.

The team of cold case experts say they have decoded a 1972 message addressed to The Portland Oregonian Newspaper that was supposedly sent by the mystery man months after the hijacking.

They claim the message contains a confession from Cooper, which ties his identity to 74-year-old Vietnam War veteran Robert W. Rackstraw.

The man dubbed by the FBI as DB Cooper, who is one of the 20th century's most compelling masterminds, hijacked a Boeing 727 at Seattle-Tacoma airport and held its crew and passengers hostage with a bomb.

Once his demand of $200,000 cash - the equivalent of $1.2 million today - was reached and transferred onto the plane, he had the crew take off before he parachuted out over the dense Pacific Northwest woods and disappeared.

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Investigators have uncovered a letter that they believe is a confession of the true identity of the infamous 1971 airplane hijacker DB Cooper

They say a letter sent to a newspaper months after the hijacking ties Cooper's identity to Vietnam War veteran Robert W. Rackstraw

Investigators dedicated to uncovering the true identity of infamous 1971 airplane hijacker DB Cooper (left in police sketch) claim they now have the final pieces of evidence that proves he is Vietnam veteran Robert W. Rackstraw (right)

The confession letter was obtained by television and film producer Tom Colbert after he successfully sued the FBI for the DB Cooper files.

He has led a team of 40 private investigators in the hunt for the real identity behind the mastermind.

The newly uncovered letter reads:

'This letter is too (sic) let you know I am not dead but really alive and just back from the Bahamas, so your silly troopers up there can stop looking for me. That 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.'

'I want out of the system and saw a way through good ole Unk,' he writes. 'Now it is Uncle's turn to weep and pay one of it's (sic) own some cash for a change. (And please tell the lackey cops D.B. Cooper is not my real name).'

Colbert gave the letter to Rick Sherwood, a former member of the Army Security Agency, to decode.

He previously decoded letters with the team of sleuths in five different notes supposedly sent by Cooper that connected him with Rackstraw.

'No one even knew about this letter,' Colbert told the Daily News. 'When I got it, I noticed it was typed just like (a different Cooper letter), so I called a code breaker and showed it to him. He said, ''Tom, you're not going to believe it, but his confession is in here,''' Colbert said.

Sherwood identified four phrases that were used multiple times – 'D.B. Cooper is not real,' 'Uncle' or 'Unk' which referred to Uncle Sam, 'the system,' and 'lackey cops.'

He used a system of letters and numbers to decode those phrases and after about two weeks, he translated 'through good ole Unk' into 'by skyjacking a jet plane' and 'And please tell the lackey cops' into 'I am 1st LT Robert Rackstraw.'

Another member of the investigation team confirmed Sherwood's findings.

This note contained coding that read: 'CAN FBI CATCH ME… SWS', which Colbert said was Rackstraw taunting agents to track him. He added that the SWS stood for Special Warfare School, which is where the veteran supposedly learned coding

Rackstraw has been on the team's radar for quite some time.

Colbert had revealed in early January that a code-breaker working for him had noticed a secret coded message in a court-released letter supposedly sent by Cooper.

He said at the time that a nine digit number typed at the bottom of the letter could have only come from Rackstraw because it referred to three covert military units he had ties to during the war.

Colbert revealed in February that his code-breaker had since uncovered the new hidden messages in four other taunting notes sent by Cooper in the late 1970s.

Coding in one note, which was sent on November 30, 1971, said: 'IF CATCH I AM CIA… RWR'.

The investigators believe the 'RWR' in the coding is Rackstraw's initials and that it also indicated that he expected a get-out-of-jail card from the federal spy agency if he was captured.

Another note contained coding that read: 'CAN FBI CATCH ME… SWS', which Colbert said was Rackstraw taunting agents to track him. He added that the SWS stood for Special Warfare School, which is where the veteran supposedly learned coding.

Colbert said two of the letters were mailed within 30 minutes of Rackstraw's old California mountain town.

Coding in this note, which was sent on November 30, 1971, said: 'IF CATCH I AM CIA… RWR'. Investigators believe the 'RWR' in the coding is Rackstraw's initials

Colbert revealed in February that his code-breaker had uncovered the new hidden messages in four other taunting notes sent by Cooper in the late 1970s, including the one above

Colbert said the letter mentioned in the article above featured coding that read 'NGJS', which he says stands for his National Guard Jump School training unit

Colbert revealed in January that a code-breaker working for him had noticed a secret coded message in this letter. He said the nine digit number at the bottom could have only come from Rackstraw because it referred to three covert military units he had ties to during the war

He added that the recent evidence supported what he has argued for some time - that the dare-devil heist was carried out a Rackshaw, who is alive and well in California.

Investigators questioned Rackstraw about the Cooper case in 1978 and eliminated him as a suspect. When Colbert first publicly named and linked Rackstraw to the hijacking, the veteran's lawyer called the accusations 'the stupidest thing I ever heard'.

Rackstraw had an illustrious military career as a pilot in the 1st Cavalry Division - one of the first major American air assault divisions.

It was there that Rackstraw learned to parachute and was given two Distinguished Flying Crosses for his performance while in the air - but he was kicked out of the army after they discovered he had lied about dropping out of high school and attending two colleges.

Colbert believes the military gave him all the skills he needed to pull off the extraordinary heist.

The FBI revealed in July 2016 that they were closing the investigation, saying that Cooper - whose real identity has never been confirmed by authorities - died of exposure in the woods between Oregon and Washington after jumping from the plane.

A nine-digit number typed at the bottom of a letter, supposedly sent by Cooper, could only have come from one person - a maverick Vietnam veteran Rackstraw

The notorious hijacker, who is one of the 20th century's most compelling masterminds, hijacked a Boeing 727 at Seattle-Tacoma airport in 1971 and held its crew and passengers hostage with a bomb

Colbert said two forensics experts said the handwriting from the letter (right) was so similar to the writing on Cooper's boarding card (left) that it was 'likely' that they 'were written by one person.'

In recent years, Rackstraw has repeatedly denied any involvement in a crime that gripped the nation

Soon after, Colbert sued the FBI to obtain reams of previously undisclosed information about the case, including the letters written by Cooper.

Four of the letters were already known to the public, but Colbert obtained the fifth letter in November in the latest Freedom of Information request he had submitted.

Copies of the typewritten letter were sent to The Seattle Times, The New York Times, The LA Times and The Washington Post by the hijacker at the time.

Colbert argues the letter, which was sent 17 days after the hijacking, proves the existence of an FBI cover-up.

'I knew from the start that I wouldn't be caught,' the letter started, before later saying 'I left no fingerprints.'

The letter wasn't public knowledge beyond a few brief reports in the newspapers that played it off as a prank, according to Colbert.

Colbert said he and his wife hired two forensics experts - one a past president of the American Society of Questioned Document Examiners and the other an ex-FBI agent - to examine the handwritten note.

The two men both said the handwriting was so similar to the writing on Cooper's boarding card that it was 'likely' that they 'were written by one person.'

Colbert said Rackstraw may have included the coded messages in the letters to signal to his co-conspirators that he survived the leap from a Boeing 727 after he hijacked it.

Colbert said his team found what they believed to be a parachute strap and foam padding (above) from skydiver's backpack in the forest near Cooper's alleged jump location last year. They turned over the two items, along with the dig site itself, to the FBI

Copies of the typewritten letter were sent to The Seattle Times, The New York Times, The LA Times and The Washington Post by the hijacker at the time

He believes other men, who were seen in a small plane in another airfield around the time of the hijacking, picked up Cooper after he landed and flew under the radar to drop him off safely so that he could make his getaway.

Colbert is adamant the FBI was too hasty to wrap up the investigation and now says the revelation of the hidden messages, especially the links to the CIA, proves why the agency has been stonewalling.

He said his team found what they believed to be a parachute strap and foam padding from skydiver's backpack in the forest near Cooper's alleged jump location last year. They turned over the two items, along with the dig site itself, to the FBI.

Colbert believes the FBI still hasn't taken action on any of the team's efforts despite what they provided them.

Colbert has spent several years conducting his own investigation into the mysterious crime, writing a book and producing a documentary series on it in the process

He has spent several years conducting his own investigation into the mysterious crime, writing a book and producing a documentary series on it in the process.

Colbert said he has extensively investigated Rackstraw as well. In 1977, six years after the hijacking, Rackstraw was suspected of kiting checks for $75,000, but fled before arrest and went to Iran to teach the Shah's men how to fly helicopters.

Meanwhile, back at home, police raided his storage units and found 14 rifles and 150lbs of dynamite. He lost his his Iran chopper job and he was brought back the USA, where he was arrested for fraud and the murder of his stepfather. Philip Rackstraw was found in the grounds of his parents' home with two bullets in his head.

Rackstraw was acquitted of murder and made bail on the fraud charge. Then he faked his death, pretending to crash his plane in the ocean at Monterey Bay, California.

He was found and taken in by the FBI, who believed he might be Cooper, but a lack of evidence and the sudden discovery of some of the hijack money in Washington - planted, Colbert says, by an accomplice - led to his release.

Rackstraw made a plea deal and after serving a year in prison for his Stockton convictions, he moved to Riverside, California.

There he taught a law course in mediation before retiring to his yacht, 'Poverty sucks'.