Olympia, Wash. ? One suspect made a deathbed confession that he was the never-captured skyjacker D.B. Cooper. Another was a fugitive at the time of the hijacking. Still another was an airline worker and former paratrooper.

Each had a face that closely resembled Cooper’s. None were him.

For nearly 40 years, the FBI has chased the ghost of the man responsible for the nation’s only unsolved hijacking, with each exhausted lead growing his stature in American folklore.

The latest example to pique public fascination — and FBI interest — is an Oklahoma woman who claims her uncle was the man who parachuted out of a plane in 1971 with a $200,000 ransom. Piecing together memories from when she was 8 years old and comments her parents made in recent years, Marla Cooper said she is certain that the legendary D.B. Cooper is actually Lynn Doyle Cooper.

She said her uncle arrived at the family home in Oregon, bloodied and bruised, shortly after the hijacking of the Northwest Orient airliner. She said she overheard her uncles talking about having hijacked a plane.

The FBI agent assigned to the case before his retirement in 1980 is skeptical. Ralph Himmelsbach is no longer involved in any part of the Cooper investigation but recalled chasing hundreds of potential suspects over the years.

“To date, none of them has panned out,” he said.

“We still do not know who is, or was, or where he came from, or where he went,” he said. “This is still a mystery.”

What investigators do know is that on Nov. 24, 1971, a man in his mid-40s and wearing dark sunglasses boarded a Boeing 727 at Portland International Airport. With a ticket under the name Dan Cooper, he took seat 18F, ordered a bourbon and water.

Then he handed a flight attendant a note: “Miss, I’ve got a bomb, come sit next to me — you’re being hijacked.”

Cooper (a law enforcement official later erroneously referred to him as “D.B.” and the initials stuck) opened a briefcase that appeared to contain explosives and demanded $200,000 and parachutes. Officials met his demands when the plane landed at Seattle-Tacoma International Airport, where passengers and two flight attendants were released.

The man in 18F then ordered the flight crew to take the plane back into the air, insisting that it fly at an altitude of no more than 10,000 feet on its way to Mexico through Reno, Nevada.

About 40 minutes after takeoff, a signal light in the cockpit showed that the plane’s rear stairway had been extended. When the jet landed in Reno, the stairs were down and two parachutes, the money and Cooper were gone.

Himmelsbach has long theorized that Cooper didn’t survive the jump into the frigid air and rugged terrain around the Washington-Oregon border. A child digging in a sand bar on the north bank of the Columbia River west of Vancouver found a bundle of $20 bills in 1980 that had serial numbers matching some of the ransom money.

There’s been no other sign of where Cooper went.