March 26, 2008 -- It's dirty and it's old, but a piece of cloth found in a Washington field might hold the key to solving one of the FBI's most enduring mysteries.
On Nov. 24, 1971, an unassuming man wearing a business suit and appearing to be in his mid-40s allegedly hijacked and threatened to blow up a Northwest Orient Airlines plane traveling from Portland, Ore., to Seattle if he did not get four parachutes and a $200,000 ransom.
When the plane landed in Seattle, the suspect, known only as Dan Cooper or D.B. Cooper, allowed the passengers and two flight attendants off the plane, and the officials handed over the money, in $20 bills, and the parachutes.
According to the FBI, Cooper simply told the remaining crew to "fly to Mexico" after they took off from Seattle.
"Back in the early '70's, late '60's, hijackings weren't uncommon. The philosophy of the day was cooperate. Comply with his demands and we'll deal with it when the plane lands," said Larry Carr, an FBI special agent who manages the case out of the bureau's office in Seattle.
In a daring getaway, Cooper jumped out of the speeding 727, thousands of feet over the Pacific Northwest, during a raging storm.
Cooper disappeared, and is still missing today, despite a massive manhunt.
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.
But no Cooper.
Countless suspects have emerged, but none have turned out to be the mystery man. In 2001, the FBI extracted a DNA sample from the J.C. Penney tie he was wearing on the flight and left behind before jumping, but that sample hasn't matched up with anyone in the investigators' sights.
Cooper's story became the stuff of lore, even a movie. Now, more than three decades later, the FBI has the possibility of a breakthrough.
Two weeks ago, two children discovered a parachute buried in the dirt, in a field approximately 100 miles south of Seattle. Investigators still need to excavate part of the chute's remains.
"It's the right color, it's the right size. It's definitely the right location, so the investigation will tell," said Carr.
He told ABC News he hopes the forensic tests on the chute will be completed this weekend.
He noted that parachutes buried in the middle of nowhere aren't something found very often, so the find could offer a big break in the case if it pans out.
But does the parachute belong to Cooper? Will they find his remains? Or is this a tantalizing clue that will again lead to disappointment? Stay tuned.