As to the explanation behind JFK's assassination, there are two primary and general schools of thought.
1. That Lee Harvey Oswald , acting as a lone gunman, shot and killed JFK.
2. That a CONSPIRACY, involving multiple "shooters" perhaps involving Oswald, perhaps not, were responsible for the killing.
Data Sources inlcude: "JFK Remembered" by Jacques Lowe & "A Question Of Character" by Thomas C. Reeve.