<<It is possible a faction within the CIA in cahoots with the mob and the Military industrial complex did. >>
You couldn't be in the CIA and NOT have contacts with both the mob and the military-industrial complex. That was one of the points of Peter Dale Scott's "Deep Politics and the Death of JFK." Scott's book was very well researched and pretty well demonstrated that no governmental or media investigation could ever get to the bottom of the assassination because of the interconnectedness of the mob, politics, "national security," law enforcement and the media. The investigators would in effect be investigating themselves.
So far, the most plausible explanation of motive that I have seen is that in the wake of the Bay of Pigs, Kennedy fired three top CIA directors, one being of course Allen Dulles, another an Air Force general whose brother happened to be the mayor of Dallas and a third guy. These guys, their supporters in the CIA and the Cuban mercenaries they employed, hated Kennedy with a passion, originally because they felt he had reneged on a promise to provide air cover to the Bay of Pigs invaders, thereby causing the death of some and the capture of the rest and then secondly, of course, for the firings. This hatred alone, however, had not been acted out, but when, shortly before his murder, JFK had begun to consider publicly the need to pull back out of Viet Nam, which to these guys looked like treason.