When was the first shot? Evidence Suggest that it was sometime prior to frame 160 of the Zapruder Film, making the duration of the assassination more than 10 seconds.

Take a careful look at frames 160 and 161 of the Zapruder film and notice a man with a billed hat in the upper right corner of each of them. In frame 160 he is clearly looking at Kennedy(you can tell by the bill of his cap). In the next frame, 161, you can see that he has turned his head away from Kennedy and is now looking up at Oswald’s window. What did he hear to make him do this? I ran this past Gerald Posner a few years ago (I emailed him and he responded). He said he thought it was compelling circumstantial evidence of the timing of the first shot. There were other people, Nellie Connally among them, who believed that that is precisely when the first shot occurred. At that moment, as Kennedy’s limo was just turning onto Elm Street, a traffic light or sign post stood between Oswald and Kennedy. Ten seconds or more gives Oswald plenty of time to fire two more shots. Thoughts?