In a news release Monday, the FBI issued a public plea for help in solving the case, which it described as "a mystery, frankly."

"We've run down thousands of leads and considered all sorts of scenarios," the FBI said. "And amateur sleuths have put forward plenty of their own theories. Yet the case remains unsolved. Would we still like to get our man? Absolutely."

All that is known of D.B. Cooper is that he bought a ticket on a flight from Portland, Ore., hijacked the plane, collected $200,000 ransom, ordered the plane to fly south and then parachuted out with the cash over the Cascade Mountains, The Columbian in Vancouver, Wash., reported.

Larry Carr, an admitted buff now the agent in charge of the case, has hopes that clues be found in $5,800 an 8-year-old boy found near Vancouver.

"Maybe a hydrologist can use the latest technology to trace the $5,800 in ransom money found in 1980 to where Cooper landed upstream," he said. "Or maybe someone just remembers that odd uncle."