I still think the Mafia had the biggest motive. But I’m not saying they didn’t work with the CIA on this. LBJ was the slickest operator in Washington. If he was involved you will never find his fingerprints.
You had a odd group who just didn’t want a second term with JFK around. The mafia were still angry over the loss of Cuba. You had Cubans who’d left and had a passion to return....who were angry. You had CIA and Pentagon folks who had an interest in the Bay of Pigs episode. They all had a piece of the ‘action’.
One curious piece to this...the year prior...in France, there was a serious attempt to kill de Gaulle. A huge investigation took place after this. Summer of 1963, it concludes. There’s a CIA connection to the attempt. De Gaulle finally picks up the phone and calls JFK...asking what the hell is going on. JFK is mystified and starts asking questions. After JFK is dead...this review over de Gaulle drops off the table. The relationship between the US and France? Doomed from that point on...no one there believes LBJ or any president that comes after that point.
The CIA has long collaborated with organized crime and gave the Marseille/Corsican drug syndicate’s enterprise to the American mob as a return favor for help with various wet works, including the JFK assassination, after destroying the French Connection for them. This on top of their Air America Golden Triangle operation moving Southeast Asian heroin to the US. The CIA is the largest drug kingpin on the planet. This is their black budget. Many books on the subject available a mouse click away on Amazon. Start here -
Organized crime certainly set up the murder of Robert Kennedy. RFK in the White House was their biggest nightmare. RFK literally did hate organized crime and wanted it crushed.