The MGB was led by Viktor Abakumov from 1946 to 1951, then by Semyon Ignatiev until Stalin's death in 1953, upon which it was merged into an enlarged Ministry of Internal Affairs (MVD).
In 1941, the state-security function was separated from the NKVD and became the People's Commissariat for State Security (NKGB), only to be reintegrated a few months later during the Nazi invasion of the Soviet Union.
The MGB essentially inherited the "secret police" function of the old NKVD, conducting espionage and counterespionage, as well as enacting a policy of supervision and surveillance to keep control and to prevent disloyalty.
Each department within the government also had their own official supervisor, a "Special Section" staffed by the MGB to keep tabs on and regulate the employees, and to ensure the absence of disloyalty.
[3] The Ministry retained a high level of autonomy and a remarkable amount of freedom of operation within the Soviet system, as the agency was only responsible to the Central Committee.
The OSO (the Special Council of the State Security Ministry) convicted arrestees charged with committing political crimes, including espionage, and could banish them from certain areas, or from the USSR entirely.
It also sought to infiltrate foreign governmental bodies, businesses, public organizations, sensitive industrial plants, cultural and educational institutions, etc., placing MGB agents in strategic posts for intelligence-gathering and possible covert action.
This involved supervising almost every aspect of Soviet life, including the intelligentsia, bureaucracy, general administrative agencies, cultural organizations, educational institutions, and even the party apparatus itself.
[11] At the beginning of the MGB, the Fourth Directorate was designed as a proto-terrorist force to combat the anti-Soviet underground, nationalist formations, and hostile elements.
[12] Viktor Abakumov dissolved this department in 1946, but kept the main players in a Special Service group so that they could continue with the same pattern of violence that the Fourth Directorate was known for.
The 6th Directorate was dissolved in 1949, and its resources and personnel absorbed into the Special Services Department (GUSS), a cryptanalysis and information security branch of the Central Committee.
They were concerned with the implementation of security programs and requirements, as well as the supervision and monitoring of the workers, leading them to make extensive use of the Special Sections within the state and local organizations.
They were able to do both outdoor (tailing) and photographic surveillance, as well as being able to tap phone lines, monitor conversations in other rooms through hidden microphones and covertly examining mail.
[18] A number of the top officials from this department were implicated in the Doctors' Plot, showing the inherent mistrust and suspicion within the Soviet security apparatus.