Marla Cooper's mom talks about brother-in-law who could be D.B. Cooper

(CBS/AP) OKLAHOMA CITY - The mother of Marla Cooper, the woman who claims she's certain her uncle was famed hijacker D.B. Cooper, gave ABC News more information as to how the man could be the convict who escaped the law.

Now, her mother, Grace Hailey, is coming forward saying she believes he could be the man as well.

"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."

Marla Cooper did not discuss on ABC how or when she reached out to the FBI, but said she recently provided investigators with a guitar strap belonging to her uncle to be tested for fingerprints. She also provided a Christmas photo of a man pictured with the same strap who she says is her uncle, Lynn Doyle Cooper.

Cooper also says that the family saw L.D. the following Christmas in 1972, after his hospital visit.  That was the time the picture she provided to the FBI was taken. She told ABC after this incident her uncle disappeared from their lives.

Federal investigators have checked more than 1,000 leads since the suspect bailed out on Nov. 24, 1971, over the Pacific Northwest. The man who jumped gave his name as Dan Cooper and claimed shortly after takeoff in Portland, Ore. that he had a bomb, leading the flight crew to land the plane in Seattle. That's where passengers were exchanged for parachutes and ransom money.

The flight then took off for Mexico with the suspect and flight crew on board before the man parachuted from the plane.

More on Crimesider
August 3, 2011 - Woman claiming to be D.B. Cooper's niece gives TV interview
August 1, 2011- "Credible" lead in D.B. Cooper hijacking case, says FBI