Corpus Christi Massacre — 'El Halconazo'

A paramilitary group known as 'Los Halcones' (The Falcons), trained and organized by Mexico City authorities, attacked student protesters on Corpus Christi day. At least 25–33 students were killed. Evidence linked the attack to Interior Minister Mario Moya Palencia and Mexico City Regent Alfonso Martínez Domínguez, who resigned. Echeverría denied knowledge — a claim that was later contradicted by the FEMOSPP investigation.