pictures taken by Abraham Zapruder, Orville O. Nix and Mary Muchmore, who were spectators at the scene.262 Substantial light has been shed on the assassination sequence by viewing these motion pictures, particularly the Zapruder film, which was the most complete and from which individual 35-millimeter slides were made of each motion picture frame.263

Examination of the Zapruder motion picture camera by the FBI established that 18.8 pictures or frames were taken each second, and therefore, the timing of certain events could be calculated by allowing 1/18.8 seconds for the action depicted from one frame to the next.264 The films and slides made from individual frames were viewed by Governor and Mrs. Connally, the Governor's doctors, the autopsy surgeons, and the Army wound ballistics scientists in order to apply the knowledge of each to determine the precise course of events.265 Tests of the assassin's rifle disclosed that at least 2.8 seconds were required between shots.266 In evaluating the films in the light of these timing guides, it was kept in mind that a victim of a bullet wound may not react immediately and, in some situations, according to experts, the victim may not even know where he has been hit, or when.267

On May 24, 1964, agents of the FBI and Secret Service conducted a series of tests to determine as precisely as possible what happened on November 22, 1968. Since the Presidential limousine was being remodeled and was therefore unavailable, it was simulated by using the Secret Service followup car, which is similar in design.268 Any differences were taken into account. Two Bureau agents with approximately the same physical characteristics sat in the car in the same relative positions as President Kennedy and Governor Connally had occupied. The back of the stand-in for the President was marked with chalk at the point where the bullet entered. The Governor's model had on the same coat worn by' Governor Connally when he was shot, with the hole in the back circled in chalk.269

To simulate the conditions which existed at the assassination scene on November 22, the lower part of the sixth- floor window at the southeast corner of the Depository Building was raised halfway, the cardboard boxes were repositioned, the C2766 Mannlicher-Carcano rifle found on the sixth floor of the Depository was used, and mounted on that rifle was a camera which recorded the view as was seen by the assassin.270 In addition, the Zapruder, Nix, and Muchmore cameras were on hand so that photographs taken by these cameras from the same locations where they were used on November 22, 1963, could be compared with the films of that date.271 The agents ascertained that the foliage of an oak tree that came between the gunman and his target along the motorcade route on Elm Street was approximately the same as on the day of the assassination.272

The First Bullet That Hit

The position of President Kennedy's car when he was struck in the neck was determined with substantial precision from the films and