The best account of the assassination of Kennedy is Lamar Waldron and Thom Hartmann's book, "Ultimate Sacrifice" (which should be made into a movie soon).

He was killed by the mafia, Roselli tried and failed in Chicago, Trafficante, in Miami,
and in Dallas, was done finally by Marcello in Dallas, who was Ruby's boss.
Harvey was set up as a patsy.

Marcello did it