During the 1960s , 1970s , 1980s , and 1990s , death squads continued to be used against anti-PRI activists , both Marxists and social conservatives . One example of this is the 1968 Tlatelolco massacre , in which an anti-regime protest rally was attacked by security forces in Mexico City . After this event , paramilitary groups like " Los Halcones " ( The hawks ) and the " Brigada blanca " ( White brigade ) were used to attack , hunt and exterminate political dissidents
Tlatelolco massacre
Tlatelolco massacre
Death squad