I believe the CIA/ FBI/ and Mafia theory best resolves the assassination case, because of the most important facts. They had the highest positions, had the most secrets that could be legally kept, & they also had control over Kennedy's body after the assassination. The mafia states: "Kennedy is bad for our business." That statement concludes that they had a grudge against J.F.K.
The CIA helped Clay Shaw, also known in some cases as "Clay Bertrand" in his legal struggle with Garrison, (believed and tried to prove that the CIA, FBI, and Mafia killed J.F.K) basically to hide their evidence of the plot to kill Kennedy and to protect their own associations. "The Secret Services came across over 400 threats to Kennedy's life, 3 of which were serious enough to entail changes in his security routine." Who killed J.F.K but none of the secret service members bothered to do anything about it. Because the CIA and FBI was so secretive, they hid important information from the Warren Commission, which evidently proves that they must have connections to the shooting and the planning of it. Sam Giancana (Mafia Boss) arranged 10,000 votes to J.F.K in Illinois toward Kennedy so that he was able to win the election in the state. Manta Lorenz says that weapons were taken to Dallas the day before the assassinated, from Miami. Sturgis Fiorini worked with Lorenz. Jack Ruby was staying at the hotel where Lorenz was staying. Ruby carried out a mob hit on Oswald to hide any evidence that he knew of.
When Kennedy was transported to Washington D.C From Dallas, while the Government had complete control of Kennedy's body, Some how Kennedy's body was taken out of the original coffin had towels unwrapped from his head and his brain removed, all with out any one aware of it. Also for some strange reason the CIA ordered for the autopsy to take place in DC rather than in Dallas.
Paul O"Conner reported the brain missing at approximately 6:45 P.