Migrants travel through Mexico's Veracruz state atop a train. The… (European Pressphoto Agency )
TAPACHULA, Mexico — With the first light of day, a team of investigators using shovels and brushes begins picking through the red dirt of the Garden Pantheon cemetery, a ramshackle resting place where a mass grave sits cordoned off by yellow police tape.
Black and blue tarps (and one advertising Coca-Cola) shield the work from the intense sun and prying eyes. Slowly, over the next weeks, the team will exhume dozens of bodies that have been dumped, nameless, in the mass pauper's grave toward the back of the cemetery, in this city near Mexico's border with Guatemala.
Some of the bodies are skeletons; others, more complete. Some died violent deaths at the hands of very bad guys; others succumbed in more mundane ways: disease, car wrecks, exposure.
Standing at the center of the operation is Mercedes "Mimi" Doretti, a forensic specialist who has pretty much seen it all. Tall with long, dark hair, the 53-year-old Argentina-born single mom has dug up bodies for two decades, from Latin America to the killing fields of Bosnia-Herzegovina.
She is fiercely protective of her charges, taciturn with outsiders, sympathetic but reserved with survivors. More than 400 people with missing relatives have given DNA samples, mostly from strands of hair, which will eventually be used in the hope of identifying the bodies.
"It's putting together pieces of a puzzle," Doretti said.
Doretti's world-renowned Argentine Forensic Anthropology Team has been brought in to conduct the exhumation through a hard-won agreement with Mexican authorities and several governments of Central America, responding to demands from family and human rights groups.
The Tapachula site was chosen in part because it is a major entry point for Central Americans hoping to travel to the United States and, for many families, is the last known whereabouts of their missing kin.
Most of these nameless dead are thought to be migrants, lost on a journey that put them at the mercy of vicious drug and extortion gangs that roam, in the words of a Salvadoran diplomat, like "a pack of wolves."
The forlorn mass grave underlines a nagging legacy of Mexico's 6-year-old drug war: How many have died, and who are they?
"Not knowing is the worst," Doretti said. "I've seen it across countries and cultures."
Each mass grave investigation is different, Doretti says.
In Bosnia, where she and other international forensic specialists identified the bodies of 3,000 Muslim men slaughtered in the 1993 takeover of the town of Srebrenica, the numbers were overwhelming.
It took months of often dangerous reconnaissance to find the clandestine burial grounds of a massacre considered the deadliest atrocity in Europe since World War II. But at least in Srebrenica, there was a finite population of survivors with whom the DNA of the bodies could be matched.
Doretti and her team also unearthed hidden bodies at El Mozote, a hamlet in northern El Salvador where the U.S.-backed army in 1981 slaughtered an estimated 800 people, more than 100 of them children. At El Mozote, identifying the dead was not as much a priority (entire families had been wiped out) as establishing the historical truth, because the Salvadoran and U.S. governments had for years denied that the massacre took place.
If the unidentified dead here in Tapachula or the dozens of other mass graves that human rights advocates say may dot southern Mexico are from an ever-moving and essentially hidden population of migrants, matching names to bones may prove next to impossible.
Mexico's National Human Rights Commission has estimated that 10,000 Mexican and Central American migrants are unaccounted for in their sojourn across this gateway nation to the United States.
The disappearances of Central Americans were a little-noticed problem until August 2010, when 72 migrants from El Salvador, Honduras and Guatemala were abducted and slain, execution-style, allegedly by gunmen from the notorious Zetas paramilitary force in the northeastern Mexico state of Tamaulipas.
Since then, Mexico has come under increasing pressure to protect the migrants who cross its territory, as well as to help find the missing. Little has been achieved, however, and only gradually has the government allowed in outside experts such as the Argentine forensic investigators. It took two years of delicate negotiations, and officials insisted on multiple layers of secrecy, according to several people involved.
"This is a very complicated process," Doretti said. "The missing can be anywhere."
Humid and leafy, Tapachula is the principal crossing for Central Americans entering the country on a path they hope will take them to the United States. But thousands end up stranded here and in other southern border towns, out of money and out of hope, begging and scraping a living, preyed upon by rapists and exploiters.
Gangs, often in cahoots with local police, demand money from the migrants from the minute they cross the Suchiate River into Mexico.