Det er nu bevist, at de lokale myndigheder allerede den 21. december i det mindste var blevet advaret om, at en massakre var under forberedelse, og at de var blevet underrettet om, at medlemmer af Den Institutionelle Revolutions Parti og et antal politifolk var involveret i forberedelsen.
It has been proved that the local authorities at least were warned of the preparations for the massacre on 21 December, that they were advised of the involvement of members of the Institutional Revolutionary Party and the police in those preparations.