D.B. Cooper

He jumped into a storm with the ransom and became the only unsolved hijacking in American history. The FBI closed the file in 2016. Open, say the sleuths.

NORJAK (1971): the hijacker parachuted with $200,000; the FBI's 45-year investigation (closed 2016, file largely released) cleared a thousand suspects; the only physical return is the 1980 Tena Bar money find ($5,800 of the ransom, weathered in ways that complicate every timeline). Citizen analysis (particle studies on the tie suggesting titanium-industry exposure) continues. The node earns its archive place as the file where investigation genuinely exhausted itself — the control case for what an unsolved thing looks like when there is no conspiracy, only absence.