Some of the witnesses describe it so well and are insulted when someone says that the sound from the knoll could have been echo from the first shots. In face of a lot pressure to say otherwise they steadfastly stuck with their experience. Cops driving their motorcycles up the knoll in pursuit of a shooter also seems pretty conclusive.
And the elephant in the room is Oswald who joined the Marines after being in a Civil Air Patrol unit run by David Ferrie. Then got Confidential security clearance right before being assigned to Atsugi airbase in Japan at exactly the time that the CIA's U2 flights over the USSR began. Oswald exits the USMC early with an honorable discharge as the U2 flights are entering their last missions. 9 days after receiving an Honorable Discharge, Oswald leaves for the USSR. He is there until Allen Dulles is fired by JFK in November of 1962. Oswald comes home with no apparent repercussions for "defecting" after having been a high security clearance Marine who worked on the U2 flights (!?).
Oswald is all over the place in 1963 -- having dinner with George De Mohrenschildt, going to ACLU meetings, then right wing rallies, then anti-Castro meetings, the Guy Bannister's office, using assumed names. He does a radio debate. Oswald distributes leaflets for Fair Play for Cuba but use 544 Camp Street as the address which is Guy Bannister's office who is ex-FBI and active in anti Castro projects. This is all in the WCR but on its face appears to show that Oswald was deeply involved in the Cold War and not all alone.