JFK, the movie, was made based on the evidence of the only court case in the history of the assassination that attempted to investigate it if my memory serves me correctly. JFK was an excellent introduction to the investigation, but there was not much new evidence to any real JFK buffs.
Issues that could be addressed in a JFK II are:
the disappearances of virtually all the witnesses from Dallas in unusual circumstances such as auto crashes which are considered an excellent way to murder people in the Mafia, these are set up in various ways;
that the Giancana that was investigated by the senate in 1976 was an absurd look-a-like of Giancana that had been recruited in Mexico who at the time was a construction worker, his murder a year or so later was considered to close the case by the FBI;
that a Dallas cop was seen behind the fence by a disappeared witness after seeing a puff of smoke from behind the fence just as the shots rang out;
a Dallas cop disappears roughly 2 weeks before the 1976 senate investigation begins with evidence he knew Giancana;
the connections between Joe Kennedy and Giancana going back to the 20’s when they organized the modern Mafia along with Bronfman, Onassis, (Hugh Hefner may be another player key in a real investigation) and fascists including European royalty are indicative of how entrenched repression of an investigation is. Its also partly religious (Protestant/ catholic), possibly its main motivation within the sphere and scope of implied criminal involvement within the government and society. The first Catholic President was successfully flouted; the fact is that the case is so important that modern history revolves around it for these reasons.
Other aspects to keep in mind are: Ruby shot Oswald to silence him from squawking, but claimed to do it out of love for JFK; Ruby ran a strip club under Mafia license ultimately and had to pull his weight if the shit hit the fan; Ruby himself began to crack like many Mafioso under interrogation, but Gerald Ford rejected his testimony at the Warren commission hearings making Ford a suspected conspirator, his own motivation of religion personally and association functionally;
LBJ ‘s mob associations and gain of power; Oswald according to Giancana’s plan was to take the fall and point to a conspiracy organized by the Cubans and Castro.
Giancana called off the assassination and the Mafia underlings put it through any way because setting it up put their heads on the line; Giancana new it was his undoing within hours of the murder; Giancana’s regime still unraveling today with shakeups in the CIA, which he once controlled its factional elements through sheer murder (elimination rather than intimidation). Its all connected to a military conspiracy that extends far beyond Giancana as the Protestant hold on world power with the collapse of British (and Protestant) power within the 20th century continues. The 2nd world war was based on these issues. Hitler was a Protestant. Hitler had extensive connections with the royalty including the British.