In the late 1980's, a Las Vegas man by the name of Bob Lazar went public with the shocking story that he had actually worked on UFOs and alien technology at a site he called "S-4", near Area 51. He claimed to have worked on the anti-gravity propulsion system of the craft, trying to figure out what makes it tick (or in more scientific terms, "reverse engineer it"). When he started to bring friends out to Groom Lake Road to watch the craft fly at night, they were eventually arrested by the Lincoln County Sheriff, and Lazar subsequently lost his job.
Initially he seemed credible, especially since in interviews with George Knapp of KLAS-TV in Las Vegas, he was able to answer some insider questions about Area 51. But later, as people began to look at his story more closely, large parts of it have been disproven. Even Lazar, in more recent interviews, has somewhat distanced himself from his earlier statements.
There is no record of him ever working for any agency related to the base, the masters degree of "electronics" that he claims to have does not exist (it is called "Electrical Engineering"), and there is no record of him ever taking classes at any of the schools or universities that he lists in his credentials. Not to mention that the "Element 115", which he claims to have identified as the fuel source of the alien craft, has since been discovered and has quite different properties than described by Lazar.
For more information see Tom Mahoods excellent article: The Bob Lazar Corner