Mexicans have come to be numbed by the relentless reports of gruesome violence this year, but the brutal scene revealed to the public on Wednesday was enough to stun them anew. Seventy-two corpses were piled up haphazardly around the edge of a breeze-block barn, arms and legs twisted over one another, waists and backs contorted into unnatural shapes. There were teenagers, middle-aged men, young girls, a pregnant woman. They had left countries including Brazil, Ecuador, El Salvador and Honduras, making the hard trek north on trains, buses and foot in search of the American dream. And then in a ranch in northeast Mexico just 100 miles from the Texas border, they finished their days, with their hands bound and bullets in their heads.
How, newspapers asked, had the situation gotten so out of control that a heavily armed gang could commit such a massacre, comparable to some of the worst atrocities in wars, in one of the country's most developed regions? And how would other Latin American countries now look at what Mexicans had done to their citizens? Throughout the debate that has taken place since the discovery, one telling word has been repeated again and again: vergüenza, or shame. "National Shame and Anger," said an editorial of Mexico City's El Universal newspaper. "With what face can Mexico condemn the violation of migrant rights in the United States when here Latin Americans are killed with impunity and their bodies buried in clandestine graves?"
But the other overarching question was more basic, and pressing. What could the perpetrators possibly gain from slaying so many innocent people? Important clues to answer this were held by a 19-year-old Ecuadorian identified only by the name Luis, who, against all odds, survived the massacre. When the gunmen fired, a bullet went through his neck and out of his jaw. He fell down as if dead but was still conscious, and after waiting patiently for hours, he got up and stumbled miles on foot until he reached an army checkpoint. Mexican marines say that Luis made contact with them on the night of Aug. 23. But suspicious that they might be the targets of a trap, they waited until Aug. 24 to gather reinforcements and make the raid in the community of San Fernando. When they went in, a gun battle left three suspects and a marine dead before they discovered an arsenal of automatic rifles and the piles of bodies. One teenager from southern Mexico was detained, but many other gunmen apparently escaped.
Luis was taken to a hospital in the city of Matamoros and then onto a Marine base, where he has been treated and interviewed by investigators. Police released a photo with his face blacked out, showing a skinny teenager, bandages across his chest and neck and tubes feeding his body. Parts of Luis' testimony have been related by Mexican officials, but journalists have not yet been able to interview him. According to the officials' account, the migrants were traveling north on a bus on the night of Aug. 21 when a group of gunmen stopped them and identified themselves as the Zetas a gang of feared drug traffickers and extortionists. The Zetas blindfolded the victims and took them to the ranch looking to rob them. However, when the migrants did not have enough to give, the Zetas said the migrants would have to work as hit men, for a salary of $500 per week. When they refused the offer, according to this testimony, they were massacred.
While more facts about the massacre need to be established, the testimony fits many accounts of previous Zetas kidnappings and extortion of migrants. The gang was originally formed in the late 1990s out of defectors from the Mexican special forces to work as enforcers for the Gulf Cartel of drug smugglers. However, they have since spread across Mexico, recruiting thousands of young thugs into their ranks and becoming a separate drug cartel as well as branching out into a range of criminal activities. Their power is concentrated across the east of Mexico, in the path taken by many Central and South American migrants heading to the U.S.
Human-rights workers have gathered accounts of hundreds of migrants kidnapped by the Zetas since 2007. In one video of such testimony shown to TIME, a man described how he was held and tortured until his family in Central America sent $2,000. "I thought I was going to die. They suffocated me with a black plastic bag. They were saying I should give them a phone number or some kind of contact with my family," he said. He then watched them torture his friend. "They were kicking him in the pants. Or one of them was holding him, as the other was hitting him with a bat." In another instance, in 2009, the Zetas allegedly kidnapped a group of 53 immigrants traveling on a train through the southern state of Chiapas and held them on a ranch. When two people tried to escape, the Zetas shot them dead in front of the rest, according to the accounts of survivors.
Migrants and residents close to the sites of such atrocities are terrified to condemn them because of fear of repercussions. The government also concedes that the Zetas have a network of corrupt police working for them. They even paid six police to help kill their own mayor in the northeast town of Santiago last week, according to prosecutors. As well as shaking down migrants, Zetas leaders arrested in border cities have also confessed to "taxing" the so-called coyotes who guide migrants through the deserts and rivers into the U.S.
President Felipe Calderón issued a statement condemning the attack and saying that gangs had taken to extortion out of desperation because they were hit so hard. "This is the result of the activity of the state against them, which has significantly weakened the operational capacity of criminal groups," he said in the statement. Calderón did not mention any extra resources against the Zetas, who are already the key target of several battalions of the Mexican army stationed in the northeast.
Governments across Latin America and international human-rights groups sent out messages on Aug. 26, demanding justice for the massacre victims. "This case once again demonstrates the extreme dangers faced by migrants and the apparent inability of both federal and state authorities to reduce the attacks that migrants face," said London-based Amnesty International, which released a recent report documenting kidnapping, rape and robbery of migrants throughout Mexico. "The response of the authorities to this case will be a test."