Mexico authorities 'knew about attack on students as it happened'
Leaked government documents say federal officials did nothing to stop disappearance and probable massacre of missing 43
Jo Tuckman in Mexico City
15 December 2014
Mexican federal authorities had real-time information of an attack on a group of student teachers  by corrupt local police, but did nothing to stop the disappearance and probable massacre of 43 people, according to new evidence published by the news magazine Proceso.
Based on leaked government documents, the new allegations are likely to further fuel public anger at the government of the president, Enrique Pena Nieto, which has insisted that federal authorities share no responsibility for the students' disappearance.
So far, 79 people have been arrested over the presumed massacre on 26 September: all are allegedly linked to a network of corrupt local politicians and police officers in the southern city of Iguala or members of a drug gang called Guerreros Unidos. 
Parents of the missing students have long alleged that federal law enforcement institutions must have known what was happening and attacked them for not intervening. Scepticism over the government account of the massacre -- and frustration with the sometimes haphazard federal response -- has propelled a string of protests against the government in recent weeks. 
The Proceso investigation  is based on documents from an initial state-level investigation which was curtailed when federal authorities took over in early October.  The Guardian has not been able to verify the magazine's account.
The documents include a detailed record of the student's movements made by a government information command post -- known as a C4 -- as the group left their college in Ayotzinapa in the town of Tixtla.
They were travelling by bus to Iguala, about two hours' drive away, intending to commandeer more buses from the city to use in a later protest.
C4 (Control, Command, Communications and Computation) posts are run by state governments, but are charged with collecting and distributing information to all local and federal law enforcement agencies within a particular area.
According to the Proceso account, the C4 informed the head of the federal police unit stationed in Iguala when the students arrived at the city's bus station at 9.22pm. About 20 minutes later, the C4 reported that gunfire had broken out, Proceso reported -- the opening volleys of what turned into several hours of violence.
Anabel Hernandez, one of the report's authors, told MVS Noticias radio station: "When we see that the federal government and the state government were following the students since they left the college in Ayotzinapa, it becomes very difficult to think that everything else that happened was an accident."
The most contentious claim in the story was that federal forces participated in the attack -- an allegation which has not been taken up by survivors of the attack.
Enrique Galindo, the head of the federal police, said there is no evidence that federal officers had participated in the events of the 26 September inside Iguala. But Galindo admitted that the 16 federal police officers stationed in the city were aware of the students' movements as they approached Iguala.
"We knew, of course, because they were in buses and they were travelling on federal highways. That seems to me to be normal. It would be worse not to know," Galindo said in an interview on the Televisa TV network. "We did not participate inside the city."
The report also questions the official version that Iguala's mayor, Jose Luis Abarca, ordered the attacks  for fear the students would disrupt an event to promote his wife María de los Angeles Pineda's political ambitions.
According to Proceso, the event finished at 8pm -- more than an hour before the students reached Iguala.
Proceso's allegations came days after a group of scientists from the National Autonomous University of Mexico raised further questions over the official version of events.
The attorney general, Jesús Murillo, says the students were detained by municipal police and then handed over to the Guerreros Unidos gang who killed them at a rubbish tip before burning their bodies. Such was the intensity of the fire, Murillo said, that the bodies were reduced to ashes and bone fragments.
In their report last week, the scientists said that evidence from the supposed crime scene did not support the theory of a mass funeral pyre.
The report by the scientists, released on 11 December, said that the pyre would have required 33 tons of logs, or nearly 1,000 tyres, to reduce 43 bodies to the remains presented as evidence by the attorney general. If tyres had been used, they said, this would also have left behind considerable amounts of metal.
Popular fury over the massacre -- and recurring allegations of state involvement -- have helped bring hundreds of thousands of protesters to a string of anti-government demonstrations over recent weeks.
About 21 people were hurt, including students, parents of missing students and federal police officers, after serious clashes broke out during a protest in Chilpancingo on Sunday.