Is 'Uncle L.D.' the notorious skyjacker D.B. Cooper? Experts are skeptical.

Could the famed skyjacker D.B. Cooper – who pulled off an audacious 10,000-foot heist on Thanksgiving Day 1971, securing his crown as the king of American folk-hero outlaws – be the man his family knew as "Uncle L.D.," a logger and Korean war veteran?

A new name – Lynn Doyle Cooper – has now been tied to the 1971 hijacking over Washington State, where a man in a suit and a JCPenney clip-on tie managed to jump out of a Boeing 727 with $200,000 ransom. The claim is meeting skepticism from the sizable community of amateur sleuths still hunting for the daredevil outlaw. It's only the latest in literally over 1,000 possible leads, most of them, the FBI has said, "junky."

"Uncle L.D. is so far just Uncle L.D.," says author Geoffrey Gray, who dug through troves of FBI files about the case to write the upcoming book, "Skyjack: The hunt for D.B. Cooper." He adds, "I think it's compelling that people want to come forward with suspects and want the case solved, but you have to have some evidence beyond memories and second-hand information."

What the FBI needs, he says, is "a forensic miracle."

The FBI has called the recent revelation one of the most promising leads yet in the 40-year-old cold case – the only unsolved skyjacking in US history. The FBI failed this week to lift a fingerprint off one of Mr. Cooper's handmade guitar straps, in an attempt to compare it to several partial fingerprints lifted from the hijack scene. The bureau says it will look for other objects from Cooper, who died in 1999.

The strap came to the FBI via a police officer who claimed to have a credible witness. That witness, it emerged this week, was Cooper's niece, Marla Cooper, who told ABC News on Wednesday that she remembers as an 8-year-old overhearing two uncles, one of them L.D., planning something "very mischievous" for the night before Thanksgiving, 1971.

The two said they were going turkey hunting, but hadn't returned by the next morning, she relates. After the story emerged of the hijacking of a Northwest Orient flight, Uncle L.D. came home bloodied and bruised, she says. He told the family he had been in a car accident, but Ms. Cooper says she later overheard her uncle say, "We did it, our money problems are over, we hijacked an airplane."

Ms. Cooper's mother, Grace Hailey, added her suspicions in an interview with ABC News on Thursday. "I've always had a gut feeling it was L.D.," Ms. Hailey said. "What I didn't know [was almost worse] than what I did know, because whenever the topic came up, it immediately got cut off again."

America's favorite hijacker

The current avalanche of news stories is just the latest chapter in a 40-year fascination with the story of the cool, collected, Bing-Crosby-look-alike who sipped a whiskey as he slipped a note to a stewardess, warning that the plane was being hijacked and he had a bomb.

The Portland-to-Seattle flight landed normally, and the man – who gave his name as Dan Cooper – managed to get $200,000 and several parachutes in return for releasing the 42 passengers on board. After taking off again, this time to Mexico, the man ordered the pilots to slow the plane and lower it to 10,000 feet, then jumped out into a stormy night with sub-freezing temperatures. The name D.B. Cooper came from a man who was questioned but cleared early on, but whose moniker stuck to the case.

In 1980, some of the money was recovered near the Columbia River, rotting in a sand bank, adding credibility to speculation that Cooper had died in the jump.

The crime inspired a 1981 Robert Duvall movie and some 17 books, many of them naming various suspects who might have pulled off the heist.

The FBI has investigated over 1,000 possible suspects and leads, some provided by authors and other amateur sleuths. In 2001, the FBI announced it had gotten a partial DNA sample from the necktie that the man left behind.

"The case is really about us, as a society," says Mr. Gray, the author. "What Cooper did reminds people of our desire to break away and be free, to not take it anymore, and to do it through an act of courage and true guts."