IMO the Oxnard call, made just minutes before the assassination, is prima facie evidence of a conspiracy. Someone in the Oxnard area had foreknowledge of the assassination. Coincidence can be ruled out. Not only did the caller say that JFK would die at 10:10 am (12:10 Dallas time), but later in the call she amended the time, saying JFK would die at 10:30 (the exact time of the assassination). It’s as if someone in the Oxnard area was actually tracking the progress of the motorcade, with the caller taking into account the delay in arriving at a known kill zone.
The details of the call as recounted by the FBI are here:
Greg Parker’s research on the call is here: