There is evidence to suggest that both Booth and Stanton were members of the Knights of the Golden Circle, or at least, strongly influenced by that organization. (See the book Shadow of the Sentinel. Booth is mentioned briefly, but the book is well worth reading).
could you enlighten those of us ignorant of the knights of the golden circle?
I heard that theory as well. There's one version of it that says that Jesse James, after faking his own death of course and going underground, went on a secret KGC mission to track down and silence Booth, who had been getting drunk and revealing secrets. That version claims that Booth was tracked down and killed in secret by the James gang in the 1890's or thereabouts.