My wife comes from a certain Sicilian family in Chicago and I can tell you that they think the mob killed JKF. Motive..revenge for Bobbie K’s attack of the mob after thehad helped JFK elected in IL. Judith Exner was a go- between the mob and JFK.
That arrogant SOB had a lot of enemies: Russians, Cubans, Mobsters (Organized Crime/Mafia), Special Agents (CIA), G-men (J. Edgar Hoover's FBI), Rednecks and Oilmen (Right-wing Extremists), and the MIC (Military Industrial Complex).
But irony of ironies, the guy who did it was a semi-literate paperback Marxist from a broken home. Just another misguided liberal.