DALLAS (AP) — Fifteen tattered $20 bills from the 1971 D.B. Cooper skyjacking sold for more than $37,000 at an auction.

That figure announced Friday was two to three times higher than expected, according to Heritage Auction Galleries of Dallas.

Winning bidders paid about $6,500 each for two of the $20 bills.

The money has the handwritten initials of investigators who examined the money when it was found buried in sand nine years after the skyjacking.

Cooper skyjacked a flight from Portland to Seattle, claiming he had a bomb.

He released the passengers at Seattle for $200,000, four parachutes and a flight to Mexico.

On that flight, he jumped out with a parachute near the Oregon-Washington border and never was found.