According to public releases from the FBI, they have closed the investigation into the only unsolved hijacking on U.S. soil in history. But two credible experts say they know who he was, but refused to think he might have been a different person using an alias.

November 24th, 1971, a man calling himself 'Dan Cooper' boarded a Northwest Orient (later Northwest Airlines) 727 out of Portland, headed to Seattle. He hijacked the plane, demanded $200,000 cash and parachutes. The plane was refueled, passengers were let off, then flew back toward Portland.

Somewhere near the Centralia-Chehalis area, Cooper, with help from the stewardess, lowered the rear fuselage ramp in the two-engine aircraft, and parachuted into the rainy, cloudy night. He was never seen again, but years later some of the money was found alongside the Columbia River.

Documentaries have insinuated he survived, and ended up in Mexico, but a very plausible explanation came from two former Federal Agents who wrote a book about it.

Former agent Russel Calame, and Bernie Rhodes, a former federal probation officer, wrote a book in 1991 called "D.B. Cooper The Real McCoy," in which they say Cooper was really Richard Floyd McCoy Jr.

They say he was a devout Mormon from Utah, who due to a dire family financial situation, masterminded the Northwest hijacking, and carried it out successfully, because he REPEATED it a few months later!

According to the two, McCoy used the fake name of Dan Cooper. It was mistakenly written down as D.B. Cooper by a journalist and it stuck. In April 1972, McCoy was captured after hijacking a plane from Denver to L.A. after demanding $500,000 and was sentenced to 45 years in prison. He escaped in 1974, and after being tracked to Virginia, was confronted by federal agents and was fatally shot after he resisted and fired at them.

The former federal agents said the FBI has possession of evidence they've never released. They say when McCoy staged the second hijacking, he changed his tactics to better his chances of success, and these tactics would have only been known to whomever hijacked the original airplane. It's the same idea as suspect who knows details of a crime that were never released to public-known only by police.

They say the FBI has evidence he took some of the $200,000 he didn't drop into the Columbia River, and went to Vegas shortly after the first hijacking. He laundered, or got rid of all the original money with traceable serial numbers, by gambling a few thousand then cashing in his chips.  There's also telephone records and a credit card receipt with McCoy's name on it corroborating his Vegas trip.

Shortly after returning from Vegas, McCoy paid off all his family's debts, and spent a lot of money, which was surprising for someone who's friends said he was poor. The former agents say the FBI didn't put the pieces together.

In addition, pictures of McCoy bear a strong resemblance to artist renderings of D.B. Cooper the hijacker.

Richard McCoy FBI Wanted Poster (FBI)

The reason they never went after him is because they had originally cleared him, and his alibi from his family he was at home that Thanksgiving weekend in 1971, having dinner with his family. They refused to believe McCoy had used a fake name.

Either way, the legend of D.B. Cooper remains perhaps the greatest unsolved legend in the Northwest, and now the FBI is done looking into it.