Robert Lazar is a scientist with two masters degrees, one in physics, the other in electronics. He wrote his thesis on magneto hydrodynamics (MHD). He has worked in Los Alamos as a technician and then as a physicist in the Polarized Proton Section dealing with particle accelerators. In his spare time, he has built a jet powered car _and_ a jet powered motorbike (max. speed 350mph!), as well as a car capable of running off of hydrogen.
In March 1989, Lazar appeared on KLAS-TV in the US claiming to have worked in an above Top Secret installation known as S-4, ten miles south of AREA 51 in the Nevada desert. He was a scientist who was employed between December 1988 and April 1989 to examine a captured flying saucer to try and reverse engineer the saucer's propulsion mechanism. He claims that there were nine different saucers at S-4, although he was only working on one of them. He was told that the crafts used a propulsion system that uses gravity waves, a theory that mainstream science hasn't discovered yet (scientists don't know what gravity actually _is_, there are many theories,but there hasn't been one that is universally accepted yet) and the energy needed is supplied by irradiating Element 115, an element not found on Earth and which cannot be synthesized. A kilogram of the element releases the same amount of energy as 47 10-megaton hydrogen bombs. He says that he had 500 pounds (227.27kg) of the element to work with, but each craft only needed 223 grams of the element. Whilst working on one of the craft, he was allowed to actually go inside the craft and he was also present at a test flight in which the craft underwent a few simple manoeuvres in the air.
When he went public in March 1989, he appeared on US TV in shadow with his voice altered, under the pseudonym "Dennis", an inside joke since his boss at S-4 was called Dennis Mariani, in an attempt to remain anonymous. On 29/3/89 he took three of his friends, one of them John Lear, to the edge of S-4 to observe any UFO test flights through a telescope.They saw (and filmed) a bright light rise in a step manoeuvre, that is, it would hover in the air, briefly disappear and reappear a few feet higher, and then the light went down in the same way. When they went again the following week on 6/4/89, they were caught by a security guard. Their ID details were recorded on a computer in Area 51 and they were ordered to leave the area, despite it being public land. They did leave and the following day, Lazar was ordered to go to Area 51 for a meeting with some security guards and an FBI agent. It was then that he resigned and left.
After he was fired at whilst traveling on an Interstate highway, he decided that he'd better go public on TV under his own name, the theory being that if anyone kills him after going completely public, then that action would prove that he was telling the truth. He went on TV to tell the full story in November 1989 and his story has (to my knowledge) remained consistent since then.