After watching Oliver Stone's "JFK" and reading "Mary's Mosaic," I had to track down another movie mentioned in the book and given high props for accuracy.
Released in 1973, just ten years after Kennedy's assassination, and shortly after the Zapruder film was made available to the public (but not used in the film), this film is unique in that it says up front that it's fiction. It says nothing in the conspiracy presented is based on evidence, but is merely "how things COULD have gone down." In "Mary's Mosaic" one of the CIA operatives interviewed said, "Watch 'Executive Action.' You could learn a lot."
The movie opened and closed rather quickly in 1973. The country wasn't ready for conspiracy theories about Kennedy's death. The movie was pretty much unavailable until its 2007 DVD release.
In the movie, the whole conspiracy isn't really explained -- a shadowy group of industrialists and FBI operatives, unhappy with Kennedy's left-leaning peace initiatives, decide to take him out -- for the good of the country. No mention of the Mafia, very little mention of the CIA. They groom Oswald for taking the fall, without his ever suspecting a thing. Meanwhile they assemble three teams of sharpshooters to do the actual dirty work.
Executive Action uses a lot of period news footage -- much of which I hadn't seen before -- and raises lots of discrepancies in the evidence and Oswald's documented movements that the Warren Commission overlooked or tried to ignore.
Not really believable, IMO. But interesting, in retrospect, and historically.
Next year 2017 the records will be unsealed. We may or may not learn anything.