more optimal spot in Dealey Plaza where the motorcade would be passing. He chose to film on top of a concrete abutment which extends from a retaining wall that was part of the John Neely Bryan concrete pergola on the grassy knoll north of Elm Street, in Dealey Plaza. Zapruder's secretary, Marilyn Sitzman, offered to assist Zapruder as he suffered from vertigo and was apprehensive about standing on the abutment alone. While Sitzman stood behind Zapruder and held his coat to steady him, he began filming the presidential motorcade as it turned from Houston Street onto Elm Street in front of the Book Depository. Zapruder's film captured 26.6 seconds of the traveling motorcade carrying President Kennedy on 486 frames of Kodak Kodachrome II safety film. Zapruder's film captured the fatal head shot that struck President Kennedy as his limousine passed almost directly in front of Zapruder and Sitzman's position, from the center of Elm Street. Zapruder later recalled that he immediately knew that President Kennedy's wound was fatal as he saw the president's head "...explode like a firecracker." Walking back to his office amid the confusion following the shots, Zapruder encountered The Dallas Morning News reporter Harry McCormick, who was standing near Zapruder and noticed he was filming the motorcade. McCormick was acquainted with Agent Forrest Sorrels of the Secret Service's Dallas office, and offered to bring Sorrels to Zapruder's office. Zapruder agreed and returned to his office. McCormick later found Sorrels outside the Sheriff's office at Main and Houston, and together they went to Zapruder's office. Zapruder agreed to give the film to Sorrels on the condition it would be used only for investigation of the assassination. The three then took the film to the television station WFAA to be developed. After it was realized that WFAA was unable to develop Zapruder's footage, the film was taken to Eastman Kodak's Dallas processing plant later that afternoon where it was immediately developed. As the Kodachrome process requires different equipment for duplication than for simple development, Zapruder's film was not developed until around 6:30 p.m. The original developed film was taken to the Jamieson Film Company, where three additional copies were exposed; these were returned to Kodak around 8 p.m. for processing. Zapruder kept the original, plus one copy, and gave the other two copies to Sorrels, who sent them to Secret Service headquarters in Washington. Television interview While at WFAA,