Mitchell's evidence is merely hearsay about Roswell?
Roswell Declassified (Popular Mechanics, 2003):
http://www.popularmechanics.com/scie...e/1281546.html
Then, amid the clutter, in Box 1, we found what we were after. It was a seemingly unimportant document titled "Morning Reports, July 1947." This was essentially a log of the day-to-day activity at the base. In much the same way that a police blotter would provide evidence of a bank robbery, the Morning Reports would provide unambiguous evidence of unusual military activity.
As we worked through the Morning Reports line by line, we came to a simple realization: Absolutely nothing extraordinary had happened at Roswell that Fourth of July weekend. There was no indication of an emergency, no mention of a deployment of rescue and firefighting crews, as was the case with other crashes. That was one mystery solved.
http://www.skepdic.com/roswell.html
Skeptics agree that something crashed near Roswell in 1947, but not an alien craft. Skeptical explanations have varied from weather balloons to secret aircraft to espionage devices. Current conventional wisdom among skeptics is that what was found on the Foster ranch was part of Project Mogul, a top secret project testing giant, high-flying balloons to detect Soviet nuclear explosions.
To skeptics, Roswell is a classic example of what D.H. Rawcliffe called retrospective falsification. An extraordinary story is told, then retold with embellishments and remodeled with favorable points emphasized while unfavorable ones are dropped.