Ayotzinapa: A Timeline of the Mass Disappearance That Has Shaken Mexico

September 26 marks the first anniversary of the night student teachers were attacked by police in the city of Iguala, Guerrero. Three students and three bystanders were killed in the attacks and 43 students were disappeared. The case sparked months of angry demonstrations in Mexico that seriously damaged President Enrique Peña Nieto's image both at home and abroad.

Twelve months on, only one of the missing students has been clearly identified by a bone fragment, and a possible match exists for a second student. The government's investigation into the atrocity also faces a mounting credibility crisis. To help readers who might be unfamiliar with this story, here is a timeline of events over the past year to aid understanding of the ongoing case.

September 26: After nightfall a group of roughly 100 students from the Ayotzinapa Normal School near Tixtla, Guerrero, enter the city of Iguala about 90 miles away from their campus. They had travelled in two busses and picked up a third along the way. They wanted to commandeer, or "borrow," more busses to use in an upcoming demonstration in Mexico City. They leave the Iguala bus station in five busses at about 9.30pm, heading back to Ayotzinapa.

During the rest of the night, municipal police and other armed men ambush four of the busses.

Three of the busses are attacked together in the same location on two separate occasions about two hours apart. During the first attack one of the students, Aldo Gutiérrez, is shot in the head, but does not die. The first attack ends with police detaining students from one of the busses and driving them away in police vehicles. The second attack takes place after other students have arrived at the scene to provide support. Local news reporters are also present. Two students are shot dead during the second attack. The rest of the students present are sent running for their lives.

One of the remaining two busses is attacked in another part of the city. All the students from that bus are detained by police.

The fifth bus is also detained, apparently by federal police. The students are ordered off the vehicle at gunpoint but the police do not open fire. The driver is given a police escort to drive the bus away.

The night also sees another attack on a vehicle carrying a youth soccer team that is leaving Iguala after a match. A 15-year-old player and the bus's driver are killed in that attack, as well as the female passenger in a nearby taxi.

September 27: The body of a fourth student, the sixth confirmed victim of the attack, is discovered. Julio Cesar Mondragon, a 22-year-old father from Mexico City, is found with his facial skin and eyes removed.

Survivors of the attacks and others attempt to locate the missing students. They go to jails and police stations but find no trace of their classmates. Some students who went into hiding begin to emerge. The final count of 43 normalistas disappeared is clearly established over the next few days.

September 28: The Guerrero state authorities arrest 22 Iguala municipal police officers in connection with the attacks, allegedly carried out in coordination with the Guerreros Unidos cartel.

A radio interview given by Mayor Jose Luis Abarca of Iguala, Guerrero.

September 29: Iguala Mayor José Luis Abarca gives a radio interview in which he says he has no information about what happened. He says he had initially heard that masked young men were disturbing the peace in downtown Iguala. "I was dancing," he remarks elsewhere.

Speculation mounts that Abarca ordered the attack in order to keep the students away from an event downtown designed to promote the political ambitions of his wife, María de los Angeles Pineda. The same event at which the mayor said he was dancing.

Mexican President Enrique Peña Nieto cancels a scheduled trip to Guerrero state. It is the first federal-level response that begins to recognize the severity of the incident.

Related: Survivors describe police attack in Mexico: 'If you moved, they fired. If you yelled, they fired.' 

September 30: Mayor Abarca requests a 30-day leave of absence.

October 1: Governor Angel Aguirre orders José Luis Abarca to "present" himself to authorities, but he is nowhere to be found.

October 4: The state authorities say they have located mass graves in the hills just outside of Iguala that could potentially hold the remains of the missing students. Authorities initially declare that 28 bodies are found there. The figure will eventually rise to 38.

The federal attorney general takes over the investigation.

October 5: The federal attorney general accepts a request by the parents of the disappeared students to allow the Argentine Forensic Anthropology Team, or EAAF, to accompany the investigation in the role of independent forensic investigators.

Related: Bodies found in mass graves could be missing students in Mexico. 

Mexican President Enrique Pena Nieto delivers remarks about the case of the missing students.

October 6: In a VICE News report, Ayotzinapa students describe the attack of September 26. They also explain the customary practice of hijacking commercial buses, and stress the neglect suffered by normal schools.

President Peña directly addresses the Ayotzinapa crisis for the first time. "Mexican society, and the families of the young students who are sadly missing, rightly demand clarification of the facts and that justice is done," Peña Nieto says, in a televised speech.

October 8: The first large-scale demonstration against the Iguala attacks and the students' disappearances takes place in Mexico City. Ayotzinapa students lead the march.

Related: Suspected student massacre shows just how bad the lawlessness has gotten in Mexico.

October 10: The United Nations Office of the High Commissioner for Human Rights releases a statement calling the Iguala attacks a "crucial test" for Mexico's government.

"What happened in Guerrero is absolutely reprehensible and unacceptable," the statement says. "It is not tolerable that these kind of events happen, and even less so in a state that respects the rule of law.".

October 11: Gov. Aguirre announces that at least some of the bodies discovered in the first set of mass graves do not belong to the missing students. This draws attention to the fact that clandestine burial sites linked to drug-war violence can be found throughout Guerrero.

Algunos de los cuerpos encontrados, de acuerdo con los avances que se tienen con los peritajes, no corresponden a los jóvenes de — Ángel Aguirre Rivero (@AngelAguirreGro)October 11, 2014

October 12: A survivor of the police attack tells VICE News that the armed men who shot at the students told them, ¨'Sons of bitches, you're getting the fuck out of here! Get on your buses and get the hell out, you're not welcome in this city!' "

October 13: Dissident teachers, normalistas, and other masked individuals storm the seat of the state government in Guerrero's capital, Chilpancingo. They hold hundreds of state employees and civilians hostage inside the building for hours before releasing them. They protesters then set the facade of the building on fire. Demonstrators also take over a bread truck, flip it over and set it on fire.

Related: Video shows government building in flames after demonstrations turn violent in Mexico. 

October 16: Peña Nieto addresses the Ayotzinapa case in public. He says that solving the case is a "priority" of the Mexican state. Students at colleges and universities across Mexico City and the country declare a two-day strike in support of the Ayotzinapa school.

October 17: Mexican attorney general Jesús Murillo Karam announces the arrest of Sidronio Casarrubias Salgado, the alleged leader of the Guerreros Unidos cartel.

October 19: A VICE News report accompanies a volunteer community police force as it combs hillsides around Iguala for signs of the missing. The volunteers describe the lackluster search efforts on the part of government officials.

Federal officials announce they are taking over responsibility for public security in 13 municipalities in Guerrero and neighboring states.

October 22: Thousands of people once again take to the streets in Mexico City. Small sympathy demonstrations are held in major cities worldwide.

Attorney General Murillo Karam says that Iguala Mayor Abarca and his wife directly ordered the attack against the students.

Related: Teachers set fire to Iguala town hall as mayor is accused of ordering attack. 

October 23: The governor of Guerrero, Ángel Aguirre, resigns under growing pressure from demonstrations in his state and around Mexico.

Gracias a todos los guerrerenses que me acompañaron, a quienes me dieron su confianza y apoyo.

— Ángel Aguirre Rivero (@AngelAguirreGro)October 24, 2014

Related: Mexico crisis deepens as governor resigns over missing students. 

October 29: Dozens of parents and family members pile into buses to travel from Ayotzinapa to the presidential residence Los Pinos in Mexico City to meet president Peña Nieto. The meeting lasts five hours and ends inconclusively for the parents, who declare that they remain frustrated and disappointed.

November 4: Fugitive Iguala mayor Jose Luís Abarca and his wife María de los Angeles Pineda are arrested in a run-down house in a poor barrio of Mexico City.

A YouTube clip showing Abarca and Pineda being arrested by federal police.

November 5: Another massive demonstration for the Ayotzinapa students takes place in Mexico City. The call for the resignation of Peña Nieto joins the traditional chants demanding the return of the missing students alive.

Esto no lo vera la TV.La red si ve a un México herido e indignado — epigmenio ibarra (@epigmenioibarra)November 6, 2014

November 6: In a press conference in Mexico City, the Americas director of Human Rights Watch calls the Ayotzinapa case the worst human-rights crisis facing Mexico since the 1968 massacre of unarmed students at Tlatelolco.

Protesters speak up at a march in Mexico City on November 5.

November 7: Attorney General Murillo Karam tells a packed press conference that the government's investigation has concluded that the attack against the students was triggered by members of the Guerreros Unidos drug gang mistaking them for rivals from the Rojos gang. He says the Iguala municipal police were working with the police from the neighbouring town of Cocula and that they handed the students they detained over to members of Guerreros Unidos.

Murillo Karam says that the missing students were almost certainly then killed by cartel executioners and incinerated in a remote rubbish dump outside of Cocula. He says the cartel operatives collected the ashes and bone fragments remaining in plastic bags and dumped these in a nearby river from where some were later recovered by investigators. He says Mexico does not have the capacity to analyze the remains, but is sending a selection to a specialist lab in Innsbruck, Austria, in the hope that DNA can still be extracted

The attorney general shows a video of three alleged gunmen confessing to the crime. He calls this version of events the "historical truth."

November 8: Ayotzinapa students and parents respond angrily to the official version and pledge to continue their protests.

A group of normalistas burn cars and trucks outside the Guerrero state government headquarters.

Protests in Mexico City turn violent for the first time. Masked individuals set fire to the 150-year-old door of the National Palace. Eyewitnesses describe Mexico City police arresting people at random, including a child and a bar hostess.

November 19: A VICE News report details instances of alleged forced disappearances in Iguala, Guerrero, at the hands of Mexican soldiers stationed in the city. A survivor of the September 26 attacks says he and other Ayotzinapa students were treated harshly by a group of soldiers who interrogated them after the police attacks.

November 20: Tens of thousands of people march from three different points in Mexico City to the Zocalo central plaza. VICE News carries live streaming coverage of the demonstration. At the end of the peaceful marches, a small group of protesters throw firecrackers and Molotov cocktails once more at the National Palace.

Related: In Photos: Here's What the Big Protest for the Missing Students in Mexico Looked Like.

November 27: President Peña Nieto delivers a national address billed by the government as a game changing response to the underlying problems revealed by the disappearance of the students. He promises a ten-step plan aimed at police and judicial reform in the country. Experts dismiss the measures as vague rehashes of old proposals. "We are all Ayotzinapa," the president says, prompting derision on social media.

December 1: Another major protest takes places in Mexico City for the missing students. Videos later circulate showing riot police pummeling demonstrators, and at least one plainclothes police officer participating in rioting.

Two new national polls show steep declines in approval ratings for Peña Nieto since the Ayotzinapa case began.

December 6: Parents of the disappeared student Alexander Mora, 19, are told that the specialist forensic lab in Innsbruck has identified DNA belong to their son among the remains found in the river. The rest of the parents rally in Mexico City and vow to keep protesting until the remaining 42 students are found.

Related: Mexico's Disappeared Students: Dispatch 1. Watch it here.

December 7: Murillo Karam says the identification of Mora backs the official version that the students were incinerated in the Cocula rubbish dump. He also announces that ex Iguala mayor José Luis Abarca and his wife will faces charges of forced disappearance.

The Argentine forensic team releases a statement that accepts the validity of the identification of Mora, but raises doubts about the government's investigation. They say there is no physical evidence linking the remains found in Cocula's river to the Cocula dumpyard.

December 9: Guerrillas from a group known as the ERPI are present at the Ayotzinapa Normal School campus and have been in contact with the students for "about a year," student leaders confirm to VICE News.

During an interview with US-Spanish language channel Telemundo, President Barack Obama offers the Mexican government help to find the missing students. "This does affect us. Mexico is our friend and our neighbor, we want them to thrive," Obama said.

December 16: Mexican newspaper El Universal publishes a report suggesting that residents of a neighboring community were forced to help the Guerreros Unidos drug cartel to carry out the students' disappearance. Witnesses quoted say members of Guerreros Unidos roamed the streets of Chilacachapa claiming that the Iguala police was being attacked by members of rival drug gang Los Rojos and rebellious students.

Related: Guerrillas at Ayotzinapa: Legacy of Armed Movements Is Present at Mexican Protests. Read the report here.

January 5: Maria de los Angeles Pineda, wife of former Iguala mayor Jose Luis Abarca, is sent to jail to face charges of organized crime. Pìneda's brothers and parents were notoriously linked to the Beltran Leyva cartel, from which the Guerreros Unidos spanned.

January 12: Parents of the 43 missing students and supporters clash with soldiers after trying to break down the gate of the 27th Infantry Battalion Base, in Iguala, with a commercial delivery truck. The protesters accused the military of being involved in the disappearance of the students.

January 20: A report published by VICE News based on parts of the case file, explores statements by alleged members of the Guerreros Unidos drug cartel who say they believed members of Los Rojos rode among the students during the night of September 26.

The files obtained by VICE News also state that on the same night as the Ayotzinapa students disappeared, 13 people were murdered in Pueblo Viejo, a place used by Guerreros Unidos hitmen to bury their enemies.

Related: The Executioners: What the Government Hasn't Revealed About the Mexico Student Massacre

February 7: The Argentine Forensic Anthropology team publishes a report highlighting inconsistencies with the government's handling of the case. It says the remains found at the Cocula garbage dump most likely belonged to victims other than the students, and the DNA samples sent by the Mexican government to Austrian experts did not match with those gathered by the Argentine team.

February 17: A caravan of Ayotzinapa parents begin a tour across the US. They are received by harsh statements from former Mexican president Vicente Fox, who tells them to "get over it" during an interview with Univision.

February 27: Attorney General Jesús Murillo Karam is removed from his post. Murillo Karam had repeatedly sparked public anger over his handling of the 43 missing students.

April 1: A group of Ayotzinapa parents post a message asking a leader of the Rojos drug gang for help searching for their children. "Please help us find our children, because this bad government has not been serious with us," the message reads. The parents tell VICE News they want to talk with the cartel, in case they have information.

Related: Parents of Mexico's Missing 43 Students are Asking a Local Drug Lord for Help Finding Their Sons

Watch the VICE News documentary 'The Missing 43.'

April 26: Parents and supporters mark theseventh month anniversary of the disappearance of the 43 students by putting up an unofficial monument in Mexico City in the shape of a +43. There are violent protests in Guerrero the following day.

May 9: A group of unknown masked gunmen enter the city of Chilapa, Guerrero, about half an hour drive from the Ayotzinapa campus and occupy the city for five days. Their withdrawal is accompanied by reports of a new mass disappearance of at least 16 people.

May 26: Demonstrations held to mark the monthly anniversary of the disappearance of the students dwindle in size and energy. Though the case remains a very sensitive topic for the government, the mass protests of the end of 2014 seem like a distant memory.

June 30: A special group of experts assembled to pick over the government's investigation by the Inter-American Commission on Human Rights complains that the government has refused to let them interview members of the military associated with the case. The government claims that it has not refused the interviews, just required necessary legal steps to ensure the case is not compromised.

July 27: Members of the group "The other disappeared of Iguala" complain to VICE News that they have had no support from the government. The organization uses their own means to search for relatives who have gone missing around Iguala. Since forming after the Ayotzinapa students brought attention to the problem of disappearances in the area, an estimated 129 bodies have been found in mass graves around the city. None correspondent to those of the students.

Related: None of Mexico's Missing 43 Students Are Among 129 Bodies Found in Mass Graves

August 8: Miguel Angel Jimenez, a community organizer and member of a self defence movement in Guerrero, is murdered by gunmen while driving his taxi. Jimenez lead unofficial searches for the students around Iguala in the immediate aftermath of the 26 September attacks, and later helped organize the relatives of the other disappeared.

September 6: The special group of experts from the Inter-American Commission on Human Rights release a report on the Ayotzinapa case. The 560-page report directly dismisses several key conclusions of the government's investigation.

The report's rejection of the possibility that the students were incinerated at the Cocula rubbish dump, which it describes as "scientifically impossible," has a major impact on the parents, who demand a new meeting with President Peña Nieto.

The report also urges the government investigation to explore the hypothesis that the police who attacked the students were actually more interested in the busses they were travelling in. The experts say there is evidence suggesting they have unwittingly commandeered a bus with heroin or money hidden inside it.

Related: Could Mexican Officials Eventually Face Charges for Failings in Missing Students Case?

September 17: Mexican authorities say they have detained of Gildardo López Astudillo. Known by the nickname "El Cabo Gil," the alleged leader of the Guerreros Unidos gang in Iguala is named within the government investigation as the person who ordered the murder and disappearance of the students.

Experts from the specialized lab in Innsbruck, where remains recovered from the river were sent for study, say they have data pointing to a possible DNA match with Jhosivani Guerrero de la Cruz. This would make De la Cruz the second student to be identified after Alexander Mora. His parents point out that the identification is only defined as "a possibility."

September 24: President Peña Nieto meets with a group of Ayotzinapa parents for the second time since the events in Iguala.

The parents demand that he set up a special investigative unit, with international support, charged with stepping up the search for their children and investigating the officials who they believe have deliberately manipulated the government's probe so far. The government says it is going to create an office for a special prosecutor to investigate disappearances in general.

Related: The Missing 43: Mexico's Disappeared Students (Full Length)

* Post last updated on September 25, 2015.