(CBS News) Conspiracy theories have existed for years, yet no one really knows the truth. What does the government know about Area 51? Who was the infamous hijacker D.B. Cooper? What really happened to John Wilkes Booth?
Author and television host Brad Meltzer investigates these mysteries and conspiracy theories for his History Channel series "Decoded," and joined the "CBS This Morning" co-hosts to discuss possible answers to some of these questions.
The thought of alien spacecraft has captured America's imagination for years and Area 51 in Nevada, which is about 100 miles northwest of Las Vegas at Groom Lake, is considered one of the biggest mysteries of our time.
Meltzer said that what is interesting about UFOs is that it is not just random people sitting at home claiming they exist, but rather some pretty powerful people have claimed to see them. In 1966, Walter Cronkite discussed the topic of UFOs on an edition of "CBS Reports," questioning if humans are alone in the universe.
"Listen, you have Walter Cronkite, one of the greatest news people of all time talking about it, this is not someone blinking a lot in a cornfield and to me, that's what is important," Meltzer said.
Former Presidents Ronald Reagan and Jimmy Carter both said they had seen an unidentified flying object, which Meltzer explained doesn't necessarily mean they saw a spaceship, but they observed something that they cannot explain.
The author also discussed the mystery of D.B. Cooper. Of all America's skyjackings, only one remains unsolved, the Northwest Airlines flight hijacked by Cooper. Meltzer explained on "CBS This Morning" that Cooper said he was going to hijack the plane, asked for $200,000 and four parachutes, and then he jumped out the back of the plane and disappeared. Meltzer calls it the "perfect crime" and claims that he has evidence of who the man actually was.
Meltzer said that bank accounts give away who D.B. Cooper actually was because he had one lifestyle before the hijacking and a completely different one afterwards. He also suddenly had $100,000 in his bank account after the hijacking.
"We think it's an inside job by a guy on Northwest Airlines. We have people in the FBI who gave us his information," said Meltzer.
Meltzer's new book "History Decoded" explores what he believes are 10 of the greatest conspiracies of all time. He includes copies of real documents to help readers decide for themselves what to make of these mysteries.