I'll always think Carlos Marcellos was behind it.
If not do so. By John H. Davis, McGraw-Hill 1989.
Synopsis: Fidel, learning of JFK/Mafia plot to bump him off, promises Mafia re-entry into Cuban Casinos for bumping JFK off.
Marcello roughly and probably illegally deported by RFK, swears vengeance.
LHO related to one of Marcello's henchmen
Also known to Cubans and KGB.
Fidel's DGI, One of the world's best intelligence services, nurtured by the KGB, had a very high level mole in the CIA at the time, as well.
My personal prejudice has always been a Fidel involvement. This book backs that up. Not hysterical.