More than five decades ago, a mild-mannered passenger in a business suit boarded a Seattle-bound flight in Oregon under the name Dan Cooper on Nov. 24, 1971. He ordered a bourbon and soda, and once in the air, handed a stewardess a handwritten note demanding $200,000 in cash and four parachutes under the threat of what appeared to be a bomb in his ratty briefcase.

The plane landed in Seattle, and authorities complied with the hijacker’s demand. After refueling, the airliner took off again. 

Somewhere between takeoff and Portland, the mysterious man jumped out of the plane and into the dark sky, attempting to hold onto the freshly acquired satchel of cash. 

He was never seen or heard from again, nor was the money ever found except for $5,800 in $20 bills that washed up on the banks of the Columbia River years later.

The only unsolved hijacking in U.S. history would lead to one of the most exhaustive investigations in FBI history as the agency vetted more than 800 suspects in one of the country’s most puzzling unsolved mysteries.