A demonstrator hols a sign that reads in Spanish "Good cop = dead cop" during a march in remembrance of the Tlatelolco student massacre, in Mexico City, Sunday, Oct. 2, 2021. On October 2, 1968, in the Tlatelolco section of Mexico City, the Mexican Armed Forces opened fire on a group of unarmed civilians in the Plaza de las Tres Culturas who were protesting the upcoming 1968 Summer Olympics. (AP Photo/Marco Ugarte)