I"m no expert on the issue, but I've lived in Western Washington since '69, and was a full-time police office for 20 years, so I try to keep abreast of developments in the case.
First off, to the best of my knowledge, NONE of the bills ( all serial numbers were recorded ) have turned-up in circulation, nor at the mint for destruction. A batch of bills were recovered from a sandy bank of the Columbia River a number of years ago; it appears they washed down to that location, and were buried ( shallow ) by the waves/currents/etc. of the river.
The location he jumped from the plane is thought to be well-known, as the door to the rear-mounted ramp ( extended ) illuminated a warning light in the cockpit, and the pilot reported it, and radar showed exactly where the was.
It was winter, Dan Cooper ( name he used, "D.B" was created by press, by mistake ) was lightly dressed. He was over a very rugged mountain range, full of canyons, rivers, tall timber, etc. The temperature, speed of the plane ( windchill ), altitude, etc, really work against the idea that he survived the jump..even if he did, hypothermia would have killed him very quickly upon landing, assuming he didn't land in water and drown, or killed himself in the landing.
Several folks have been very closely investigated by FBI ( they still have an active, open case on it ), and all were excluded as suspects. Every now and then people speak up, claiming they were "D.B,", usually "deathbed" statements to press, kids, grandkids, etc., but all have been excluded upon investigation...much like Jesse James claims, or Billy- the -Kid claims.
Western Washington is a real jungle in spots, lots of rain, lots of very thick underbrush,very limited roads,trails, etc. I think the best guess is he either hit water, drowned, and money washed away, some to be found as mentioned above; or he did land on the ground,died, and his body and/or money was eventially washed into creek/river/then into the Columbia.
Having said all that, IF he waited until he was in Nothern Nevada / California ( high desert, Alturas area, if that is in flight pattern ), he might have gotten away with it. Even now, what, 30 years of so later, there are area's there that are extrodinarilly dark at night ( very little population ), and it would have been relatively easier for him to figure out exactly where he was..particularly if he had a confederate on the ground, helping him. Of course, this is before GPS which would have helped him, as well as NVG's, etc.
All in all, an interesting piece of American folk-lore, as well as being the basis for quite a few books, etc.
A tavern in the area he is thought to have jumped over holds an annual D.B. Cooper festival each aniversary.
Mark
