There is an article on Wired about a manual the CIA paid magician John Mulholland to write. All known copies of the manual were supposed to be destroyed in 1973 but it survived and is being reprinted and sold. The article also mentions historical use of other magicians by the government. Some of the links in the article are worth checking out as well.
Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.