Aguas Blancas massacre (June 28, 1995). Guerrero state.
One of 17 violent incidents against popular organizations (as compared to 42 against the PRD and 4 against the PRI) in 1995 alone.

In the official count, 17 farmers are killed and more than 20 injured. Members of the South Mountain Range Farmer Organization, a countryside offshoot of the PRD that had joined the party in the 1988 election and then rebelled against a parent organization it saw as too slow-moving, are driving to a rally to demand the release of a peasant activist who had been arrested (and never reappeared). They also want restriction of local logging operations, better farmworker wages, higher teacher salaries, less police violence, and an end to arbitrary arrests of anyone protesting these issues. The Governor, Rubén Figueroa, the fifth in his family to govern Guerrero, follows a policy of “much police, little politics.” His father had often been photographed preparing to meet his constituents by loading his rifle and six-shooters and dealt with unrest by, as he explained, exterminating it: “when you kill a rabid dog, you kill the rabies. When you kill a guerrilla, you kill the guerrilla war.”

The farmers were ambushed by motorized police bearing automatic weapons and insulting them (survivors remember remarks like “here’s your democracy by voice,” “is that what you want? huh?” and “this is what is happening to you for being troublemakers”); some of them are shot point blank. Weapons are subsequently placed in the farmers’ hands, allowing the police to claim self-defense. The police videotape the confrontation and edit out the part where they open fire, “proving” that they are innocent. In their version, somebody seen only from the back aims a pistol at the police. The narrator explains that this is one of the farmers, then cuts to shots of dead farmers with pistols in their hands. Figueroa says that “aggression against the police” caused the massacre.

This attempted coverup does not work. Unlike what ensued in the aftermaths of 1968 and 1971, this time newspapers like Reforma and La Jornada aggressively pursue the case in both investigative reporting and editorials, reflecting the growing strength of civil society since the 1985-88 period. (For instance, shots taken right after the massacre show no guns, but later ones do.)
The full video is eventually leaked, which opens the floodgates, sort of.

One newspaper columnist observes that “the broadcast of the video achieved in less than a month what looked impossible: it forced the president of the republic to request the intervention of the Supreme Court and led to the resignation of the governor”; for his part, the Governor calls the whole thing “fundamentally an affair of the press.”

The subsequent Mexican Supreme Court review of the case notes that “it is well known that to sustain a lie you have to continue lying,” calling state representatives’ claims “absurd…in their uncontrolled effort to cover up, mislead, and protect [themselves].” It describes the state government as “a clique holding power that it had to protect, even when it implied hiding the truth,” says the police “fired compulsively and indiscriminately” and blames the Governor, the Secretary-General, and State Attorney General. Nonetheless, no criminal action against any of these officials ensues (the central government sends it back to the state, which decides not to prosecute its own governor), though the Governor is dismissed and 28 police officers and 4 government officials are arrested, if only briefly. Some of them claim that the peasants “got what they deserved.” The governor later writes an article blaming the massacre on subordinates who ignored his orders to try to carry on conversations with peasant leaders instead of shooting them. A year later, the EPR (Popular Revolutionary Army) arises; it carries out 44 attacks over the next two years, killing, by government account, 57 soldiers and police officers. Ten years later, protestors still complain about continuing impunity for the perpetrators.