Retired Col. Robert Friend, a former director of the Air Force's nearly 20-year UFO study, Project Blue Book, says that science should continue looking into the mystery of flying saucers.

Friend, assigned in 1958 to direct Blue Book, was charged with trying to determine if UFOs were a threat to national security and whether they could be of scientific interest.

"When I first took over the program, I wrote two staff studies, and in both instances, I recommended that [UFOs] be put into another agency which would give them full scientific investigations and analyses," Friend told The Huffington Post over the weekend at a special lecture titled "Military UFOs: Secrets Revealed."

The event, held at the Smithsonian-affiliated National Atomic Testing Museum in Las Vegas, featured Friend, seen below, three other retired military colonels and a former United Kingdom Ministry of Defense UFO investigator.

These days, the retired 92-year-old colonel acknowledges that he's spoken to more Air Force pilots than most people will ever meet, and he's heard their stories about strange things they've encountered in the sky -- objects that have come very close to their aircraft.

Despite the roughly 700 UFO cases labeled as "unidentified" during the Air Force's investigation of more than 12,000 reports, Blue Book was closed down in 1969. The project's conclusion: UFOs posed no security threat to the nation, nor did they display any technological abilities "beyond the range of present-day scientific knowledge."

But Friend, who was Blue Book director until 1963, didn't totally agree with the official findings.