Prove it is connected to Kennedy's assassination. Just because someone has a motive to commit murder doesn't necessarily mean they're guilty.
The point is that it has everything to do with the assassination.
The CIA was carrying out attacks against Cuba even after the CIA failed Bay of Pigs operation and the missile crisis, Kennedy promissed Kruschev that America would stop clandestine operations against Cuba. The CIA disobeyed a direct order and carried out an operation against Cuba from Star Island (commanded by Frank Sturgis), Kennedy found out and raided that CIA camp. The CIA then carried out another operation against Cuba from this CIA camp (commanded by E Howard Hunt). This was the second CIA camp Kennedy raided.
CIA also disobeyed the Whitehouse on 2 occasions in Viet Nam.
This is motive, which make the CIA suspect.
Arthur Kroc 1963 article
http://www.jfklancer.com/Krock.html In it
The Whitehouse forwarns of a coup coming from the CIAThere is more then enough evidence to know JFK assassination was a conspiracy, this is just one piece.
Daniel Sheehan has an incredible talk on JFK assassination that illustrates how factions became aligned and why they were motivated to do so.