The mystery of D.B. Cooper

A serial number and the date Feb. 21, 1946, were stamped on the parachute found in Washington state. The FBI, with the help of parachute experts, determined that the parachute had no connection to the D.B. Cooper case.  (Kevin P. Casey / Associated Press)

Some of the $20 bills that were given to hijacker D.B. Cooper. The money was found by a boy on the banks of the Columbia River in 1980. It is the sole link to the only unsolved airline hijacking in U.S. history.  (Nick Ut / Associated Press)