At some stage he refused to work and was transferred to another Soviet prison-camp. In December 1955 he was one in a group of detainees handed over by the Soviets to the East German authorities at Frankfurt (Oder) which, following border changes mandated ten years earlier, had become a crossing point between the German Democratic Republic and Poland. However, in view of his official status, which was given as "non-amnestied war criminal", he was not immediately released. Sources comment on the contrast between the "war criminal" official status accorded him by the Soviet authorities in 1955, and the career damage Stempel sustained from his refusal to join the Nazi Party between 1933 and 1945. On 28 April 1956 Stempel was released from the . He was able to flee to West Berlin where he obtained clerical work. From West Berlin, in collaboration with West Germany's Justice Minister, Thomas Dehler, he campaigned for the release of Karl Hamann. The campaign succeeded: Hamann was released from prison in October 1956 and permitted to flee to West Germany in May 1957. In consequence of his treatment in the Soviet Union, Stempel never fully recovered physically. He died in Celle on 22 October 1981.