How did the Zapruder film help solve the case of the assassination of JFK?

I'm writing a term paper, but I can't seem to find any information on this anywhere. I am looking for how modern technologies were used in the examination of the JFK assassination, and in what way was the film crucial to the investigation and solution of the case.|||marshal, do you need a special tool to change the click/button.. i want to change it for the glow in the锘?dark one..