It's been 53 years since DB Cooper hijacked a plane and disappeared into the night, forever.
But we may finally be about to find out exactly who he was thanks to an item from a decade before the infamous crime.
Checking in for his flight under the name Dan Cooper, DB became an internationally known criminal for hijacking Northwest Orient Airlines Flight 305 on 24 November, 1971.
Given the name DB Cooper by the press in the aftermath of the incident, he threatened to blow up the Boeing aircraft if he wasn't given $200,000 and four parachutes.
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After securing the money and method to escape, Cooper jumped out of the plane while it was thousands of feet up in the sky.
He was never found and to this day his identity and fate remain unknown.
The FBI even closed the case in 2016, meaning no one is officially trying to find out who he was.
But one man, Eric Ulis, has made it his passion project to find out who the real DB was.
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He's been investigating the case for more than a decade, and now feels he could possess an item that will solve the mystery once and for all.
It comes as Ulis last week revealed that he was able to secure a DNA sample from the tie DB Cooper left at the scene.
And with modern forensics have advanced to a point where we can learn so much from microscopic evidence, Ulis says he has identified traces of stainless steel and titanium from samples.
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It's pointed him towards a now closed Pennsylvania steel company which supplied many of the materials aircraft manufacturer Boeing used to build their aircraft.
Eyes are now staring at research engineer Vince Petersen, who died in 2002.
And if it's not him, then Ulis says Petersen 'likely rubbed shoulders' with whoever Cooper really was.
Speaking to Fox News, he said that Petersen's job would have given him knowledge of how the plane worked, and that Boeing had a 'significant downturn' in 1971 which may have affected the man's livelihood.
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Crucible Steel workers also often travelled to Seattle due to their connection to Boeing, and the flight DB Cooper hijacked was heading there.
Speaking to LADbible, Ulis said he had managed to speak with Petersen's family.
While adamant their father is not Cooper, they have shared with him an envelope from Petersen that dates back to 1961.
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The item is brimming with Petersen's DNA, which combined with the a modern DNA sampling technique of metagenomics could mean Petersen is identified as Cooper by the end of the year.
It could, of course, not be him but the envelope's DNA gives Ulis the ability to rule him out and carry on with the investigation.
Ulis told LADbible: "He's definitely a compelling person of interest in my mind and I'm certain that if he wasn't DB Cooper he rubbed shoulders with DB Cooper. He'd have known the guy without even knowing it.
"Fortunately his daughter has surrendered to me an envelope with a letter included that he sent to his mother in 1961.
"The stamp is still in place and the envelope is in fact still sealed at the back and torn down the edge to get the letter out.
"This was before the days of self-sticking stamps and envelopes so his DNA is on there and affords me the opportunity to sequence Vince Petersen's DNA and do a direct comparison to what we come up with from the tie.
"The thing that's beautiful about that is we know one way or the other.
"It's very help irrespective of what happens.
"I think Vince Petersen is helping solve this case either way.
"He's been spoken about as a person of interest because he happens to have come from the lab where all the attention is focused on.
"The evidence seems to point in his direction, for sure."
Ulis believes that following on from securing a sample of DB Cooper's, finding out his identity is now only a matter of time due to advanced DNA sequencing.
He also believes it was the final jigsaw piece in what was needed to finally put a name and face to the crime.
Topics: DB Cooper, Crime, True Crime, US News, Science, Weird