The mother of Marla Cooper, the woman claiming to be the niece of D.B. Cooper, also believes that her brother-in-law is the infamous skyjacker, and has provided further details about the man who could be the daring culprit in the decades-old case.
Marla Cooper recently came forward to the FBI with evidence that she believes proves that her uncle Lynn Doyle Cooper is the famed D.B. Cooper, the man hijacked and threatened to blow up a commercial plane flying to Seattle in 1971, then parachuted to the ground with $200,000 in hand.
Her mother, Grace Hailey, told ABC News that she doesn't remember much about that Thanksgiving in 1971 where her brother-in-law returned to the house in Sisters, Oregon, but she believes he could be the hijacker. Hailey's statements are one reason why the FBI thinks the tip from Marla Cooper is credible.
"I've always had a gut feeling it was L.D.," Hailey told ABC News. "I think it was more what I didn't know is what made me suspicious than what I did know, because whenever the topic came up it immediately got cut off again."
Hailey says that L.D. grew up in Sisters and was familiar with the area where the hijacker jumped -- a fact that is consistent with the FBI's theory that D.B. Cooper knew the Pacific Northwest. He was also a war veteran, which matches the theory that the hijacker had a military background.
L.D. Cooper was a logger and an outdoorsman -- tough enough, Hailey believes, to leap out of plane into the wilderness. His soundness of mind, her daughter feels, is a different story.
"I think a man who was willing to jump out of airplane, in the middle of an ice storm over a forest, doesn't have his wits about him," Cooper told ABC News.
Marla Cooper has told ABC News that she has provided the FBI with a guitar strap and a Christmas photo of a man pictured with the same strap who she says is her uncle, Lynn Doyle Cooper.
She is working on a book about her belief that her uncle is the hijacker, but that is not her main motivation for coming forward.
"I contacted the FBI as soon as I was sure that what I was remembering were real memories," she said. "There's a crime that's taken place that hasn't been solved and I'm the only one, as far as I know who knows what happened."
Marla Cooper told ABC News that L.D. Cooper was a Korean War veteran, but he was not a paratrooper. She thinks he lived in the northwest, had children and died in 1999. She said he remained isolated from his family.
Steve Dean, the assistant special agent in charge of the criminal division of the Seattle FBI office, confirmed Wednesday to the Seattle Times that Marla Cooper had contacted the bureau and turned over items to assist in the investigation.
She says that the family saw L.D. the following Christmas in 1972, after his hospital stay -- which was when the picture she provided to the FBI and to ABC News was taken. After this her uncle quickly faded from their lives.
One key reason she is convinced that her uncle was D.B. Cooper is his sudden disappearance from the family after that Thanksgiving.
"I definitely think it was strange that he kind of disappeared like that," she said, adding that she does not think he was a bad man. "I don't think he was evil, and I think he regretted it."
He worked with leather and made the guitar strap that she has turned over to the FBI.
The FBI is now searching the guitar strap they received for fingerprints at their forensic lab in Quantico, Va., which will be checked against partial fingerprints obtained from the hijacking. Meanwhile they are hunting for evidence to prove L.D. Cooper was on that plane in 1971.
"It's a very unique case...Agents have been actively assigned to it and it's passed on from generation to generation...of agents that have worked leads as they have developed," said Brad Garrett, an ABC News consultant and former FBI profiler.
Garrett said the FBI is likely examining the life of Marla Cooper's uncle for more clues that he could be the infamous D.B. Cooper.
"Does this guy's background actually fit someone that could have pulled this off because this guy did have a proficiency in a 727 plane, how low it would fly, how slow it would fly and that you could jump out the back of it," Garrett said.
After he received the money in $20 bills and the parachute, he ordered the plane to take off for Mexico. Cooper then did the unthinkable when he lowered the back stairs and jumped out of a speeding 727, thousands of feet over the Pacific Northwest during a raging storm.
He disappeared, despite a massive manhunt that has become the stuff of legend and even a 1981 movie. Throughout the years many leads in the case have became dead ends, and it remains the only unsolved hijacking in U.S. history.
The case was reignited when a male suspect's name was given to the FBI by a law enforcement agent, as was a guitar strap. Sources familiar with the case confirm that it was Marla Cooper who prompted the latest flurry of investigation.
So far no fingerprints have been found on the guitar strap, and the F.B.I. will not officially comment on the case.
"My two uncles, who I only saw at holiday time, were planning something very mischievous. I was watching them using some very expensive walkie-talkies that they had purchased," she said. "They left to supposedly go turkey hunting, and Thanksgiving morning I was waiting for them to return."
A day later, Northwest Orient flight 305 was hijacked, and her uncle L.D. Cooper came home claiming to have been in a car accident.
"My uncle L.D. was wearing a white t-shirt and he was bloody and bruised and a mess, and I was horrified. I began to cry. My other uncle, who was with L.D., said Marla just shut up and go get your dad," she said.
Marla Cooper is now convinced there was not a car accident, but that her uncle was injured crashing to earth in a parachute. She says that she also remembers a discussion about the money that day.
"I heard my uncle say we did it, our money problems are over, we hijacked an airplane," she said.
It later became clear, however, that there was no money. It is believed that the hijacker lost much of the cash as he came crashing down.
Marla Cooper says that her two uncles wanted to return to search for the cash, but her father refused. She believes this was because the FBI search was just beginning to take shape.
After that Thanksgiving Day she never saw her uncle again. She was told he died in 1999.
In 1980, the case was put in the spotlight once again, after a young boy found $5,800 in $20 bills from the ransom money decomposing along the banks of the Columbia River.
According to Marla Cooper, two conversations with her parents initially made her suspicious. The first was in 1995 with her father just before he died.
"My father made a comment about his long lost brother, uncle L.D. And said he thought he was still alive but hiding from the FBI, and I questioned why he would be hiding … he said don't you remember he hijacked that airplane?" she said.
At the time she was unable to embrace such an incredible story. But in 2009 it came up again while speaking with her mother.
"A couple years ago my mother made a comment, another comment, a similar comment that she had always suspected that my uncle L.D. was the real D.B. Cooper," she said.
She said that her uncle was obsessed with the Canadian comic book hero Dan Cooper, and even had one of the comic books thumb-tacked to the wall. She added that she thinks her uncle didn't expect to survive the hijacking.
The FBI also obtained a partial DNA sample from the black JCPenney clip-on tie Cooper left on the plane before jumping out. The FBI extracted the sample in 2001.
FBI spokesman Fred Gutt told the Seattle Times Monday that little contradictory information has emerged that would rule out the possible suspect. The FBI has determined a guitar strap that belonged to the man is not conducive to lifting fingerprints. But the case agent is trying to obtain other items with better surfaces to lift fingerprints, Gutt said. Gutt said Wednesday the case isn't a high priority, but the information can't be ignored.