On the night of 26 September 2014, a group of students in the Mexican state of Guerrero were ambushed by municipal police as they traveled in a convoy of buses through the city of Iguala.

Five people, including two students, were killed when the officers opened fire on the buses, and another student was later found dead, his body showing signs of horrific torture. Forty-three other students simply disappeared without trace.



A government investigation soon concluded that the police – in the pay of a local drug gang called Guerreros Unidos – mistook the students for members a rival drug gang known as Los Rojos.

As the first anniversary of the events approaches, however, momentum is growing behind the hypothesis that real target of the attack was not the students – but the bus they were traveling in.

Speculation has focused on the theory that the students unwittingly commandeered a vehicle which was carrying a hidden shipment of heroin or money, which the corrupt police officers were dispatched to hunt down and recover.

“The hypothesis that the students were confused with a rival gang has been completely discounted,” said Carlos Beristain, one of a group of independent experts assembled by the Inter-American Commission on Human Rights to pick over the government’s investigation into the massacre.

“The hypothesis about the bus is strong. There are elements pointing to it, and it would explain the modus operandi of that night.”

The students’ disappearance unleashed a wave of public outrage fueled equally by attack itself and the narco-corruption which has enabled criminals to infiltrate local governments across the country.

Anger also focussed on the government’s apparent tolerance of such corruption which, for many, implied a degree of federal complicity in the horror.

Under pressure to prove it was serious about getting to the bottom of the case, the government agreed to allow international experts access to its investigation.

The report’s conclusions have in turn contributed to anger over the case, and are expected to help swell the numbers at demonstrations planned this Saturday to mark the first anniversary.

“They tried to confuse people with all the vile lies they told,” said Manuel Martínez, a tutor at the missing students’ teacher-training college. “The report has given us new energy. It has given the movement new life.”

The report draws on police and army communications that show that the students’ movements were monitored by security forces from the moment they left their college in the town of Ayotzinapa aboard two buses.

The official logs also indicate that the security forces knew the students were on a mission to get more buses to carry protestors to another demonstration, something they did regularly – and usually peacefully – after a negotiation with the drivers.

The experts also say there is nothing to indicate that anybody, not even Guerreros Unidos, was particularly concerned about the students’ presence in Iguala until they sought to leave the city. By then they had three more buses in their charge.

The report has focused its attention on one of these additional vehicles, the so-called “fifth bus”.

Piecing together fragmented evidence referring to the bus in the early stages of the official investigation, the experts concluded that the “fifth bus” is the only one that was stopped by federal police, rather than shot by municipal police.

It was also, they say, the only bus where the students were ordered out at gunpoint, but not actually attacked, and the only one that was driven away from the scene.

After that the “fifth bus” simply disappears from the case file, without explanation.

“We are not making judgements and we are not speculating,” expert Beristain said. “We are dealing only with the evidence that has produced an uncomfortable truth.”

The hypothesis that the bus may have had hidden valuable cargo also draws from the fact that the mountains beyond Iguala are one of the main areas for opium poppy production in Mexico.

“The [heroin] business that moves through the city of Iguala could explain the extreme violence and massive nature of the attack ... due to the existence of a bus that had been taken by the students but not detained. Until now this line of investigation hasn’t been explored,” the report concluded.

The report also highlights an unrelated indictment in Chicago of eight alleged Guerreros Unidos traffickers.

The ring, according to the Justice Department statement announcing the charges in December 2014, “worked with various narcotics sources in Mexico to import wholesale amounts of heroin and cocaine from Mexico to Illinois, often concealing the narcotics in commercial passenger buses”.

A DEA agent supported the charges in an affidavit that contains translated fragments from intercepted telephone conversations in 2013 and 2014.

“Your aunt gets here between 8 and 9 in the morning with the kids. The other lady arrives at 7 to 8,” said one of conversations between two of the defendants.

Prosecutors argue that the “aunt” and the “other lady” were code for buses, and “kids” for heroin. One of the numbers monitored in the Chicago case has an Iguala area code.

The government has responded cautiously to the report, welcoming its findings as a contribution to uncovering the whole story, while choosing to ignore the questions it raises about the credibility of its investigation.

“Today we have more elements to help us clear up these unfortunate events,” said President Enrique Peña Nieto earlier this month. He did not mention the fact that the official version has not changed since November when it was described as the “historical truth” by his then attorney general.

“The case is still open,” Peña Nieto added. “The investigation continues.”