INSIDE EDITION Speaks to the Woman Who Says Her Uncle Was D.B. Cooper

INSIDE EDITION speaks to Marla Cooper, the woman who has come forward claiming her uncle was the legendary hijacker D.B. Cooper.

New details are emerging about the bombshell claim that legendary skyjacker D.B. Cooper has finally been identified after 40 years.

Marla Cooper spoke to INSIDE EDITION about her uncle, Lynn Doyle Cooper, who she calls Uncle L.D.

She's shocked the world by saying he was D.B. Cooper, the hijacker who parachuted into legend from the rear of a passenger jet in 1971 with $200,000 in cash and was never seen again.

Marla, a 48-year-old divorced mom from Oklahoma City, told INSIDE EDITION she passed an FBI polygraph test after going to them with her story.

"They have told me they really never doubted me," said Marla.

Marla says she was eight years old when she eavesdropped on her uncle, who was badly injured, confessing to her dad on Thanksgiving, the day after the daring skyjacking.  

Her dad swore her to secrecy, and told her she could never tell anyone what she overheard.

"He said, 'This is a matter of life and death, and your Uncle L.D. could die for what he's done.' "  

L.D. Cooper lived in Sisters, Oregon, not far from where the FBI believes D.B. Cooper may have landed after he jumped from the Northwest Orient jet.

Marla says L.D. was a huge fan of a comic book hero named Dan Cooper, an Air Force paratrooper.

"I think he romanticized or identified himself with that comic book character," she said.

We had to ask her what many are wondering: why would her uncle hijack the plane using 'Cooper,' his real last name?

"I don't think he was in his right mind. Why would a man jump out of an airplane, why would he hijack an airplane? The paratrooping part isn't part of his official military record."

She says he was a Korean War veteran and an old war injury may have contributed to his undertaking such a risky crime.

"I think that he was probably suffering from [a] brain injury from his time in the Korean War."

Marla says she's now working on a book about her jaw-dropping story, but says that's not the reason she's coming forward after 40 years. She became emotional, telling us she hopes she can help other troubled veterans like her uncle.

"I hope that by coming forward with this that...I would like to do something for the veterans," she said.

L.D. Cooper died 10 years ago. The FBI says while they have nothing to confirm Marla Cooper's story, they've come up with nothing to dispute it either.