A group of independent investigators, including retired FBI agents, are asking the bureau to take another look at a 1971 skyjacking that has become an enduring mystery.

A Northwest Orient Boeing 727 passenger jet was hijacked over the Pacific Northwest on November 24, 1971.

The hijacker was given a $200,000 ransom, then parachuted from the plane and was not seen again.

He was never positively identified, but became known as D.B. Cooper.

Tuesday, the FBI announced it’s closing the 45 year old investigation.

A group of independent investigators wants the bureau to look at evidence they’ve gathered.

They say their evidence points to Robert Wesley Rackstraw, 72, a Vietnam veteran who is a former pilot and paratrooper.

When contacted by CBS2 news by phone, Rackstraw said the independent investigation was full of holes. He also told a CBS2 reporter to “Do your own diligence,” before hanging up.