I assumed that I had turned as I described a moment ago, placing my right hand on my left leg, that it hit my wrist, went out the center of the wrist, the underside, and then into my leg, but it might not have happened that way at all.[C3-257] The Governor’s posture explained how a single missile through his body would cause all his wounds. His doctors at Parkland Hospital had recreated his position, also, but they placed his right arm somewhat higher than his left thigh although in the same alinement.[C3-258] The wound ballistics experts concurred in the opinion that a single bullet caused all the Governor’s wounds.[C3-259] THE TRAJECTORY The cumulative evidence of eyewitnesses, firearms and ballistic experts and medical authorities demonstrated that the shots were fired from above and behind President Kennedy and Governor Connally, more particularly, from the sixth floor of the Texas School Book Depository Building. In order to determine the facts with as much precision as possible and to insure that all data were consistent with the shots having been fired from the sixth floor window, the Commission requested additional investigation, including the analysis of motion picture films of the assassination and onsite tests. The facts developed through this investigation by the FBI and Secret Service confirmed the conclusions reached by the Commission regarding the source and trajectory of the shots which hit the President and the Governor. Moreover, these facts enabled the Commission to make certain approximations regarding the locations of the Presidential limousine at the time of the shots and the relevant time intervals. Films and Tests When the shots rang out the Presidential limousine was moving beyond the Texas School Book Depository Building in a southwesterly direction on Elm Street between Houston Street and the Triple Underpass.[C3-260] The general location of the car was described and marked on maps by eyewitnesses as precisely as their observations and recollections permitted.[C3-261] More exact information was provided by motion pictures taken by Abraham Zapruder, Orville O. Nix and Mary Muchmore, who were spectators at the scene.[C3-262] 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.[C3-263]