A woman says she knows the identity of D.B. Cooper, the nickname given to the man who carried out the only unsolved plane hijacking in U.S. history: her uncle.
"I'm certain he was my uncle, Lynn Doyle Cooper, who we called L.D. Cooper," Marla Cooper told ABC News.
Four decades after the skyjacker parachuted out of a U.S. jetliner in midair over the Pacific Northwest and vanished with $200,000 in cash, federal agents have acknowledged they are pursuing new clues pointing to a suspect they believe is long dead.
PhotoBlog: Could this be the real D.B. Cooper?
On Wednesday, Marla Cooper of Oklahoma City told ABC News she is the source behind the new leads. She said her uncle, Lynn Doyle Cooper, who died in 1999, was behind the skyjacking of a Seattle-bound Northwest Orient Airlines flight from Portland, Ore., on Nov. 24, Thanksgiving eve, 1971.
A man calling himself "Dan Cooper" slipped a note to a flight attendant after takeoff saying he had a bomb, then opened his briefcase to reveal red-colored sticks attached to a mass of wires.
The plane landed in Seattle, where he freed the 36 other passengers in exchange for $200,000 in cash from the airline and four parachutes. He kept several crew members aboard and ordered the plane to fly to Mexico.
The man ended up jumping out of the back of the jetliner into the night with a parachute and the ransom money somewhere between Seattle and Reno, Nev., over what was believed to be a rugged, wooded area.
Marla Cooper said she was 8 years old when she saw her uncle a few days after the skyjacking at a family gathering at her grandmother's house in Sisters, Ore. — not far from where D.B. Cooper is believed to have jumped out of the plane.
She said her uncle was wearing a white T-shirt and was "bloody and bruised."
"I asked him what happened. He told me that they’d been in a car accident. My other uncle who was with L.D. said., 'Marla, just shut up and go get your dad.'"
Marla Cooper told ABC she ran inside the house but continued to eavesdrop on the uncles' conversation.
"I heard my uncle say, ‘We did it. Our money problems are over. We’ve hijacked an airplane,’” she said.
Marla Cooper said her two uncles wanted to return to the area to look for the cash, but her father refused, apparently fearful of an FBI search that was beginning to take shape, according to ABC.
The skyjacker was never found, and only $5,800 of the ransom money turned up when a child digging in a sandbar on the north bank of the Columbia River west of Vancouver in 1980 unearthed a bundle of $20 bills. It's not known what happened to the rest of the cash.
After that Thanksgiving Day Marl Cooper said she never saw her uncle again. She said she was told he died in 1999, ABC reported.
She said in 2009, her mother made a comment that "she had always suspected that my uncle L.D. was the real D.B. Cooper."
Marla Cooper eventually contacted the FBI with her suspicions and provided them with a guitar strap to check for her uncle's fingerprints. The FBI was reportedly unable to lift prints to check for a match.
The FBI won't publicly confirm that Marla Cooper is the person behind what the agency characterizes as a "promising lead" in the D.B. Cooper case.
Special Agent Fred Gutt in the bureau's Seattle office said only that the agency is "attempting to identify some physical evidence that maybe can help corroborate" the person's story.
"It's early enough on that we haven't identified inconsistencies yet" to discredit the story, Gutt told msnbc.com.
"The case is 100 percent unsolved as of right now. Unless or until we can obtain additional evidence it will remain that way," he said, classifying the case as "low priority."