Well, this is interesting: the FBI recently unveiled The Vault, a collection of recently unclassified documents. And, naturally, everyone is intrigued by the few revelatory snippets about the decades old alien sightings in New Mexico.
There's one particularly fascinating passage, shown above with the Day the Earth Stood Still image, by a special agent in the FBI's Washington field office who described in detail the "recovered" flying saucers and what their alien pilots purportedly looked like.
The document in question seems ripped right out of a '50s science fiction movie, beginning with the special agent's name: Guy Hottel. Apparently, Guy wrote a memo explaining that the saucers were identified by the U.S. government's high powered radar in New Mexico. The radar interfered with the "controlling mechanism" of the saucers. The saucers, described exactly how you'd think they look (round, silver, retro-looking discs) were "recovered," with three alien bodies inside. He wrote:
You can view the whole thing here. In somewhat of a tease, it doesn't appear as if any more information about Guy Hottel's memo was released or contextualized. The FBI Vault lists Hottel simply as "a Special Agent in Charge of the FBI's Washington Field Office. The information concerning Mr. Hottel is in regard to a March 22, 1950, memo he sent to the Director concerning flying saucers."
Another not-nearly-as-interesting declassified aliens document (view all documents related to "flying discs" here) is noted by The Telegraph. It concerns itself with a 1949 patrol of a policeman, army guard and highway patrolman near Salt Lake City who were astonished to see a "silver coloured object high up approaching the mountains at Sardine Canyon" that "appeared to explode in a rash of fire."
Cue the X-Files theme song.
Update: Apparently Guy Hottel has been floating around the FBI's website for years now, reports CBS News. And even though the "mystery" continues, Hottel's memo has had one tangible effect: traffic to the FBI's site is surging.