 Standing near the curb at the corner of Houston and Elm Streets, he took a series of color slides immediately before, during, and after the assassination.Willis appears in the Zapruder film until frame #206, just prior to Kennedy disappearing from view behind the Stemmons Freeway sign.During the assassination, Willis snapped a 35mm color slide (the fifth of twenty-seven he captured in Dealey Plaza that day) showing the presidential limousine and its occupants, the United States Secret Service agents' follow-up car and occupants, parade onlookers, and the grassy knoll visible in the background.