At first glance the Raúl Isidro Burgos teacher training college in Ayotzinapa, Guerrero, could be mistaken for a tourist resort: a cobblestone path leads to a colonial ranch with courtyard and fountain attached while children splash around the swimming pool and tables await diners in the elegant restaurant.

As you get closer, the picture changes. The original hacienda was expropriated after the Mexican revolution and now the classrooms and kitchen cater to 500 students. The walls are plastered with combative murals; portraits of Che Guevara, Lenin and Marx gaze down at new arrivals.

The first-year students sleep eight to a room, mattress and blanket on the floor, surviving on coffee, beans and rice. The curriculum combines agricultural science with sports and radical protest. The graduates obtain a teaching certificate along with a sense of social justice, putting both to work in rural communities.

In the past 30 years successive Mexican governments have sought to curb the influence of these rural colleges, shutting several down and drawing up plans to convert the remaining campuses into tourism training centres.

On September 26th last year a group of Ayotzinapa students travelled to nearby Iguala to raise funds, unaware that the mayor, Jose Luis Abarca, and his wife, Maria de los Angeles Pineda, deeply involved with the local Guerreros Unidos mafia organisation, were hosting a political event.

Police opened fired on their buses, killing six people, including a taxi driver and a member of a local football team.

The injured and dead lay unattended for hours while more students arrived, alerted by their friends. Police then detained 43 students and handed them over to mafia gunmen. Since then, just one of the missing students has been identified, by DNA, his remains found in a rubbish dump.

On the run

The mayor and his wife went on the run, along with the local police chief and his deputy. A number of cartel members were detained and confessed to the crime, describing how the students were shot dead, their bodies set on fire, the remains dumped in a nearby river.

Prior to these events Mexican president Enrique Peña Nieto, who assumed office in 2012, had negotiated the “Pact for Mexico” with opposition parties, opening the door to economic reforms. He also persuaded citizens that the epidemic of violence was on the turn and that a new centralised police force would replace discredited local officers.

Ayoztinapa changed everything. Mexico exploded in anger and support for Los 43. The parents of the missing students held rallies all over the country and put their case to the United Nations at a special meeting on forced disappearances. At home Angel Aguirre, the governor of Guerrero, was forced to step aside and Peña Nieto held a meeting with anguished parents, promising justice.

By November parents and students had lost patience at the slow pace of the investigation. Attorney general Jesús Murillo Karam put an end to a press conference with the unfortunate “Enough, I’m tired”, a phrase which was widely circulated and mocked.

Students raided and emptied a chain of convenience shops in the state capital, Chilpancingo while vans delivering snacks and fizzy drinks were seized, their contents distributed to the public. In a further round of protests, government buildings were set on fire, highway toll booths occupied and commercial vehicles seized.

While the Ayotzinapa protests enjoy widespread sympathy across Mexico, Chilpancingo is divided as the town fears further disruption. In January Peña Nieto announced it was “time to move on”.

Empty chairs

Back in Ayotzinapa, the school serves as a reception centre for visitors and a planning hub for parents who still cling to the hope of seeing their loved ones return.

In the outdoor basketball court 43 empty chairs sit in rows, a photo on each while candles flicker and an image of the Virgin of Guadalupe is imprinted on a blackboard. A Christmas tree bears handwritten messages pinned to its branches; “My dearest son, I’m still waiting for you, come back soon, you will always be my baby”.

Gabriel Hernández Lozano (19) is a first year student who once shared a room with 10 others. Four went missing on September 26th, two more were killed that night, another injured. Three of his friends opted not to return to the college. “Now there’s only me”, he said, gesturing at the empty room. “Sometimes I can’t sleep; it feels like the others are here.”

Parents have organised search expeditions, uncovering more than a dozen shallow graves, a reminder that thousands of Mexicans have gone missing in recent years, their cases forgotten.

The investigation has yielded 99 arrests, including 58 police officers, along with the fugitive mayor and his wife. The police chief and his deputy remain at large. On January 27th Murillo Karam presented what he called “the historic truth”, based on the confessions of cartel gunmen and partial DNA results. The government believes the bodies of the students were incinerated in a large area of waste ground, and the remains dumped in a nearby river.

More loose ends

The Argentinian Forensic Anthropology Team (EEAF), hired by the parents of the missing students, cast doubt on the official version, citing procedural errors in the work of the attorney general’s office (PGR). The Argentinians are waiting for further DNA results before drawing their conclusions, a process that may take months.

The government is keen to move ahead with state elections scheduled for June, but students reject the idea of business-as-usual and are determined to disrupt them. In recent weeks the Mexican army has been drawn into the controversy, after it emerged that soldiers at the 27th Infantry Battalion army base, located less than two miles from the scene of the shootings, failed to intervene in the abductions, even though they are tasked with fighting organised crime.

Fresh wounds

Guerrero state is the home of numerous guerrilla movements hunted for years by army troops. One prominent leader,

Lucio Cabanas

, graduated from Ayotzinapa. In the 1970s army troops rounded up rebel suspects, “disappearing” them inside the barracks. The wounds of that era are still fresh; information is still leaking from dusty archives and parents of

Los 43

have demanded permission to search the barracks, where the army operates a crematorium.

Ayotzinapa faces other challenges in the coming months: classes are suspended and many students have gone home. In recent years graduates have applied for teaching jobs in the cities, abandoning their traditional rural vocation. The government has offered an injection of funds but until the case is resolved, students and professors refuse to negotiate.

The electoral authorities are in hiding, their offices forcibly shut down, setting the scene for a violent showdown between police and protesters in the coming months.

The interim governor, Rogelio Ortega, is a former radical who was tortured by the Mexican army and was recently denounced as having close ties to Colombia's Farc rebels. Ortega was selected in the hope that he might calm spirits in the restless state.

As long as the case of Los 43 remains unresolved, however, that goal seems unlikely.