I'm not a great believer in conspiricy theories for the simple reason that human beings are so unreliable. It would only take one person with a shred of proof making it as far as the press and the secret would be out. I don't believe that as many people as it would take to protect the theory would be loyal to it because people are basically untrustworthy. Also, it's surprising how many times that the people who shout loudest about conspiricy theories tend to live in a trailer in the wilds of New Mexico and are called Billy-Bob.