Everyone along the parade route were not firing weapons. Neither are innocent as they both chose to fire a weapon in an area that they were unsure of where the rounds would go with a sign telling them no shooting. They both are negligent and are both responsible for his death. Though not intentional it was negligent.So charge everyone who was along the parade route as the second killer of JFK?
Same mentality. Obviously not. One of the 2 didn't kill anyone. It was not a conspiracy. There was no intention of killing. There is the legal responsibility for every bullet that you fire. Ok give them separate trials and convict them both independently.
So now you have sent an innocent man to prison. As my DA friend used to say. "I would rather let a hundred guilty men go free, than to send one innocent man to prison "