PORTLAND, Ore. (KOIN) -- The 51st anniversary of the D.B. Cooper hijacking at Portland International Airport is two weeks away and an amateur investigator has revealed new leads in the case.

In Downtown Vancouver Friday morning, Eric Ulis shared a picture of the man he now thinks was D.B. Cooper.

The man, Vince Petersen, died in 2002, but Ulis now thinks that he is the man behind the 1971 skyjacking.

Petersen coincidentally shares an almost identical last name to Sheridan Peterson who was considered for many years to be D.B. Cooper.

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Peterson passed away in 2021 at the age of 94, and Ulis says he eventually ruled him out as a suspect.

Ulis says he traced a rare form of titanium found on the black tie the D.B. Cooper left behind on the Boeing 727 to a laboratory where Petersen worked near Pittsburgh, Pennsylvania.

"The titanium lab consisted of about 8 men. That's it," Ulis said. "A very small universe of engineers who worked in the titanium research lab. The men in the research lab did wear ties. We have photographs of guys in the research lab wearing ties."

Ulis is asking for people who remember Petersen to contact him to help fill in the blanks.

He says the current owner of Petersen's house is allowing him to search the property for the ransom money, parachute, briefcase, or any other clues about D.B. Cooper.