What the flight crew knew
On November 24, 1971, a man who gave his name as Dan Cooper bought a ticket from Portland to Seattle on Northwest Orient Flight 305. During the flight he told a crew member he had a bomb and demanded cash and parachutes. The plane landed in Seattle, where he received $200,000 and parachutes. The passengers were released. The plane took off again with members of the crew aboard.
Somewhere after that departure, the man went down the plane’s rear stairs and vanished. The FBI’s account describes the jump, but the precise point where he left the aircraft, his landing place and whether he survived are separate questions. Search areas depend on assumptions about his exit time, the aircraft’s path and the weather.
The cash turned up without its owner
In 1980, a boy found deteriorating bundles of bills on a bank of the Columbia River. The FBI identified them as ransom money. The serial numbers gave investigators a way to establish where the bills came from. The find tied a physical object back to the original crime, something that many later stories about a possible hijacker could never do.
The discovery gives the bills a reliable last location. How they reached that spot is harder to establish. Cash can move separately from a person, and a riverbank discovery leaves open when the bills arrived and what carried them there. Finding one portion of the ransom also leaves the fate of the rest of it unknown.
A name is easy to propose and hard to prove
The FBI says it had considered more than 800 suspects by the fifth anniversary. A plausible resemblance to a sketch, an interest in aircraft or a claim made by a relative can generate a lead. Each detail has to be tested against the date of the hijacking, records of the suspect’s whereabouts and any evidence that puts that person on the plane.
The nickname has added a small confusion of its own. Dan Cooper is the name in the FBI’s account of the ticket purchase. D.B. Cooper is the name by which the case became famous. Searching only the famous name can obscure which parts of a later retelling came from the original record.
What happened to the investigation
In July 2016, the FBI said it had redirected resources away from the active investigation and would preserve its evidence. It specifically distinguished new physical evidence involving the money or parachutes from the many theories it had already received. The recovered cash remains valuable because it is evidence investigators could tie to the hijacking. It still leaves the identity of the passenger and what happened after his jump unresolved.