I’ve read much about this mystery, as well as others.
If I recall correctly, some money was found by a boy many years later in a creek bed in the supposed area he jumped. They were too decayed to be in circulation, but I believe serial numbers or something were matched. It was only a fraction of what he had jumped with, though.
Additionally, a woman came forth saying she believed her uncle (or maybe great uncle) was D.B. Cooper based on the story, his personality, and just some odd circumstances that seemed to be more than coincidence. I think he had died and that’s why she put her story forth, but I don’t remember what came of it.
Kind of in a related vein, there was a guy recently that was offering evidence to the FBI and police departments in regards to the unsolved cases of the Zodiac Killer and the Black Dahlia. He proposes that his father (or maybe stepfather) is the killer in all of those cases, as well as the killer of victims not yet discovered in the southwest for decades. It was interesting and plausible, but I’m not sure it turned out? Gonna go google it now…