The 4th Auxiliary Police Bureau of the Civil Police of the Federal District[1] was a Brazilian political and investigative police division that operated in Rio de Janeiro from 1922 to 1933. It was based in the Central Police Building, under the jurisdiction of the Chief of Police of the Federal District and the Ministry of Justice, while being politically directed by the Military Cabinet of the Presidency. Although its jurisdiction was limited to the Federal District, its investigators could operate in other states and even abroad. Succeeding the Inspectorate of Investigation and Public Security (1920) and preceding the Special Delegation of Political and Social Security (DESPS) (1933), the 4th Police Bureau was a precursor to Rio de Janeiro's DOPS and served as a model for similar organizations in other states.
The division had a specialized police force, distinguishing it from other auxiliary and neighborhood bureaus. Three of its sections — Social Order and Public Security, Political Security, and Supervision of Explosives, Weapons, and Ammunition — carried out political police functions, although political surveillance was not its sole mission. While monitoring political groups was not new to the police, its institutionalization was relatively recent. The bureau's primary activity was intelligence gathering through infiltrated agents, informants, wiretaps, and surveillance of suspects in public spaces, workplaces, and homes. This resulted in a large volume of reports and statistics, systematically shared with other state agencies. Its agents also conducted arrests, and its facilities held detainees before their transfer to prisons, from where they could be exiled from the capital.
The immediate reason for its creation was the rise of the tenentist movement, which necessitated an entity to protect the First Brazilian Republic's government from a series of military conspiracies. Thanks to the political police, many conspiracies were dismantled before escalating into revolts. Similar police reorganizations were occurring in other countries in response to the revolutions of 1917–1923. The 4th Bureau's agents targeted military personnel, members of the political elite, anarchists, communists, and common criminals. During most of the long state of emergency under president Artur Bernardes (1922–1926), its head was major Carlos Reis, under whom the prisons became overcrowded, and the police were accused of torture and even killing detainees, notably in the Conrado Niemeyer case. Before and during the Constitutionalist Revolution of 1932, the 4th Bureau persecuted conspirators and propagandists opposed to Getúlio Vargas' government.