Mexico is struggling through its deepest crisis in years. The protest movement triggered by the Sept. 26 disappearance of 43 students in the state of Guerrero has unsettled Mexico’s political establishment more deeply even than the student movement of 1968, or the Zapatista uprising of 1994, because this movement touches the entire political spectrum.

“Fue el estado” (“The state did it”) is the slogan on the lips of many. But what this means is unclear.

When the scandal broke out, responsibility was confined to local officials. Obeying orders from Iguala’s municipal president, Jose Luis Abarca, and his wife María de los Angeles Pineda — both leaders in the Guerreros Unidos drug cartel — police shot and killed six students and captured 43 others.

According to taped confessions, the abducted students were then handed to gang members who later executed them and burned their bodies in a municipal dump.

At first, then, the portion of “the state” that was responsible was the municipal government of Iguala, a town of 118,000 inhabitants, that was run from top to bottom by a drug cartel. Statements issued by one of the students’ alleged killers also suggested the possibility that other nearby state organizations — including the Raul Isidro Burgos Normal Rural School , the teacher-training school that the students attended — were infiltrated by competing drug organizations. Indeed, it appears plausible that municipal governments and police forces of much of Guerrero state are controlled by drug organizations, the more so because the Iguala region is the center of a thriving opium-producing region.

Had this been the only fact uncovered by Iguala’s tragic events, the stain of the massacre might have damaged just the parts of the Mexican state run by drug organizations, and not the legitimacy of the state as a whole. But party politics have turned events into a national crisis.

Both the Iguala and the Guerrero state governments are run by the most established party of the left, the Partido de la Revolución Democrática (PRD), while the presidency is in the hands of the centrist Partido Revolucionario Institucional (PRI). This initially encouraged President Enrique Peña Nieto to assume a low profile, and to try to let the Guerrero state government take the rap for attrocities committed in their jurisdiction. Indeed, the political fallout of the scandal appeared to open vistas for the PRI to re-take Guerrero state in the next election.

Passing responsibility between federal, state and local governments has been a tradition of Mexican politics since the country’s democratic transition. During the worst years of scandal over feminicide in Ciudad Juárez, for instance, the country stood aghast as the mayor of Ciudad Juárez, the governor of Chihuahua, and the federal government blamed each other for the crisis.

At the early stages of the current drama, the PRD imploded under the weight of its undeniable responsibility, leading to the resignation of state governor Angel Aguirre and to the fragmentation of the party. But the event’s stains did not stay neatly on the PRD or in Guerrero, and moved quickly to the National Palace in Mexico City. How did that happen?

When Mexico’s attorney general’s office stepped into the investigation, the Federal Police found a mass grave with 38 bodies in it. Naturally, they initially believed that they had found the missing students, but it turned out that there were other, unidentified, occupants in that particular mass grave. The public now had to account for 43 missing students, plus an additional 38 vicitims of another atrocity. Then another mass grave was found, also filled with unidentified bodies, followed by yet another.