The Soviet secret police agency responsible from 1934 for internal security and the labour prison camps, having absorbed the functions of the former OGPU. Mainly concerned with political offenders, it was especially used for Stalin’s purges. Its leaders were Yagoda (1934–36) Yezhov (1936–38), and Beria until 1946, when it was merged with the MVD (Ministry of Interior). After Beria’s fall in 1953 the Soviet secret police was placed under the KGB (Committee of State Security).