Did Oswald act alone?

Or was it a conspiracy? Was it part of the industrial military complex? Was Nixon involved? LBJ- Johnson? Was the CIA and the Mafia involved? In order to have pulled off the shots that killed JFK, Oswald would have had to have been an expert marksman. Every factual piece of evidence shows that Oswald could not shoot a fish in a barrel. As we now have a committed to change President in office, should we be re-examining how JFK was inated instead of blindly accepting the Warren Commissions findings?