This report recounts the operation of the detention, torture, and imprisonment of the Brazilian exile Jefferson Cardim de Alencar Osario, along with his son, and his nephew, in Buenos Aires on 11th December 1970 and their arrival at Buenos Aires port from Colonia (Uruguay). The operation was coordinated and carried out by military attachés belonging to the Brazilian embassy in Buenos Aires and agents of the Coordinación Federal (Federal Coordination) of the Argentine Federal Police.