JFK was killed as a joint effort between Ben Gurion and the CIA. JFK first threatened to break the CIA into a thousand splinters or some such and then he was ignoring Ben Gurion's plea to protect Israel (Ben Gurion wrote a letter to JFK that read, "Mr. President, my people have the right to exist. And right now, that right is being threatened"). JFK also said something about Dimona, Israel's nuclear program. I don't remember the details of what he said, but clearly it didn't sit well with Ben Gurion. I think he was telling Ben Gurion to stop pursuing nuclear weapons, or something.
Look up Michael Collins Piper's book. It was an underground best-seller. In fact, Piper is listed as a "conspiracy theorist" by the highly dishonest Wikipedia. This is almost a ringing endorsement of how honest and well-researched his book was.
See book here:
The Mossad Role in the JFK Assassination Conspiracy
It's completely free.