His tenure as Secretary of the Interior during the Díaz Ordaz administration was marked by a notorious increase of political repression in the country; dissident journalists, politicians and activists were subjected to censorship, arbitrary arrests, torture and extrajudicial executions. This culminated with the Tlatelolco massacre of 2 October 1968, which put an end to months of social protests across the country; Díaz Ordaz, Echeverría and Secretary of Defense Marcelino Garcia Barragán have been considered as the intellectual authors of the massacre, in which hundreds of unarmed protestors were killed by members of the Army. The following year, Díaz Ordaz appointed Echeverría as his designated successor to the Presidency, which he assumed on 1 December 1970.