Read “The Late Great U.S.A.”. He thinks that 9/11 was part of a staged plot to bring about the NAU.
I may be wrong, but I don't remember seeing it. I sure as heck don't want to check that book out of the library again.
Full disclosure: I've ripped Corsi up-and-down over the NAU stuff.
On pages 30-32, Corsi discusses Robert Pastor's comments that a 9/11-type crisis may force the U.S. government to make decisions that it wouldn't otherwise. I think (emphasis on "think") that's about as close as Corsi gets to being a Truther. (And I don't think it's enough).