The initial Roswell story was based on the crash of a balloon used to study radioactivity in the atmosphere. At the time (in 1947) it was a classified program called Project Mogul. The debris which was found was positively identified as balloon remains, along with some radar reflectors.The incident was blown out of proportion at the time because it happened to coincide with the first "flying saucer" sighting to get big media coverage. Subsequently, the whole thing was forgotten for 30 years, not even making it onto the "Top 100 UFO sightings" list put out in the 70s.
Then, in 1978, the National Inquirer published a story on Roswell. Witnesses suddenly started popping out of the woodwork with stories of alien bodies and military conspiracies, which brings us to where we are today.
The Pentagon thoroughly investigated Roswell and published two reports, the most recent called Roswell: Case Closed in 1997.
Of course, the UFO nutters claim that the Pentagon is just part of the conspiracy, so there's no hope of convincing them merely by presenting a detailed report with all the evidence, is there?
Yet another pitiful attempt at disinformation.