 On July 22, 1964, Willis provided testimony to Wesley J. Liebeler, assistant counsel of the Warren Commission, at the Post Office Building in Dallas.Twelve of Willis' color slides with descriptions served as "Willis Exhibit 1" for the Warren Commission.Willis testified to the Commission that his fifth photo was inadvertently snapped when, just after he had prepared his 35mm Argus camera to capture a photo, he was suddenly startled by a gunshot related noise (the first of three shots he remembered hearing), and his finger that was already on the camera shutter button reacted to the gunshot related noise, then, he quickly depressed the button and the fifth photo was captured.