 The killings ended only when an American helicopter crew, headed by Warrant Officer Hugh Thompson, Jr., discovered Calley's unit in the act and threatened to attack them with his aircraft's weapons unless they stopped.One of the soldiers on the scene was Ron Haeberle, a photographer for the newspaper "Stars and Stripes", who took unobtrusive official black-and-white photos of the operation through the lens of his military-issued camera and color shots of the massacre with his personal camera.Although the operation appeared suspicious to Calley's superiors, it was forgotten.