Other evidence discovered over the years according to KOIN News 6 includes Cooper's clip-on tie and clasp. FBI forensics experts apparently used it to extract the hijacker's DNA and perhaps fingerprints.
Update D.B. Cooper 12-7-11: Investigators are attempting to link fingerprints left behind on the airplane with fingerprints obtained from the toothbrush of L.D. Cooper. The suspect's niece, Marla Cooper, alerted authorities about her suspicions. Suspicions about Relative. Marla says her uncle was injured when he visited her family's home in Sisters, Ore. the day after the hijacking. However, her uncle claimed that his wounds were from an automobile accident. The mystery should soon be solved by the fingerprint analysis.