 As an "Obergefreiter" (equivalent to Private First Class) he was charged with interrogating captured American fighter pilots after he became an interrogation officer in 1943.He has been highly praised for the success of his techniques, in particular because he never used physical means to obtain the required information.Scharff's interrogation techniques were so effective that he was occasionally called upon to assist other German interrogators in their questioning of bomber pilots and aircrews, including those crews and fighter pilots from countries other than the United States.