My thoughts are that Cooper died that night. He must have landed in the water and died. His “fanny pack” of money that he secured before he jumped dislodged and some bundles of money spread out. His body, dragging the parachute (with cords), was most likely caught up by one of the propellers of the LARGE boats that traversed the waters, and eventually became untangled.

The place where the money was found YEARS LATER, had been a place of dredge deposits. Most likely came from upriver and deposited there.

Every bill of the hijack money had its serial # recorded before Cooper got his hands on it. Besides the bills found years later, not one was ever found in circulation.