It is a fact that Zapruder testified that a shot came from behind him no matter how much you ignore it.
It's a fact that Zapruder did not conclude that he knew where the shot came from, no matter how much you want to ignore the influences of others in the heat of the moment.
Mr. ZAPRUDER - Yes, actually--I couldn't say what I thought at the moment, where they came from--after the impact of the tragedy was really what I saw and I started and I said--yelling, "They've killed him"--I assumed that they came from there, because as the police started running back of me, it looked like it came from the back of me.
Mr. LIEBELER - But you didn't form any opinion at that time as to what direction the shots did come from actually?
Mr. ZAPRUDER - No.