MATAMOROS, Mexico (Reuters) - Bereft Mexican families stand clutching photographs of loved ones, weeping outside a morgue on the country's northern border in search of victims of the worst mass killings in Mexico's drug war.
Ricardo Martinez, 63, is one of many grief-stricken parents who have come to the city of Matamoros on the border with Texas for news of their missing children since soldiers began digging up dozens of bodies from mass graves in nearby San Fernando.
The last time Martinez spoke to his son Elvis was when the 33-year-old called from a pay phone two weeks ago to say he was getting onto a bus so he could sneak into Texas from the border state of Tamaulipas to look for work in Houston.
The next news he got was from coroners informing him his son was one of nearly 150 bodies unearthed since last week in graves that have become a stain on the name of Tamaulipas.
"The only thing my son wanted was a job so he could try to get ahead. Here in Mexico you lose your life for aspiring for something better," said Martinez as he left the coroner's office Saturday with his weeping daughter.
Camped out in Matamoros, the Martinez family is one of a growing number who suspect their relatives were among those hauled off buses by hitmen and murdered by the feared Zetas cartel that the government has blamed for the atrocities.
Mexican President Felipe Calderon is struggling to avert a collapse of law and order in Tamaulipas, home to natural gas fields near the Gulf of Mexico, as the Zetas fight the powerful Gulf cartel for smuggling routes and extend their control over large areas, infiltrating police and local governments.
The state is a magnet for migrants planning to cross into the United States illegally or who seek work in the thousands of factories on the Mexican side of the border.
The roads of Tamaulipas are a major thoroughfare for buses that gangs are now hijacking, kidnapping passengers for ransom and forcing some to join the gangs.
"Given what's happening, we'd rather add hours to our journey times than go through San Fernando," said Juan Armando Gonzalez, who runs an office for the Omnibus chain.
Inhabitants of Tamaulipas like 47-year-old Jose Tovar say the bodies found so far are just the tip of the iceberg.
"I don't think we're looking at 146 or 200 dead, I reckon there are over a thousand buried in hidden graves," he said.
BLOW TO CALDERON
The slayings in Tamaulipas are a bitter blow to the government's efforts to reassure Washington and the rest of the world that it is winning the war against the cartels that Calderon launched on taking office in December 2006.
"It's bad news for Mexico and for foreign investors," said Jose Luis Pineyro, a security expert at Mexico's Autonomous Metropolitan University. "Calderon is trying to sell the message that Mexico is a safe and peaceful place."
Armed with grenade launchers and automatic weapons, both the Gulf cartel and the Zetas have orchestrated mass jail breaks and driven police from rural towns, while the latter are openly stealing gasoline from state-run pipelines in the area.
More than 37,000 people have died in the violence over the past four years, hurting the hopes of Calderon's conservatives of retaining the presidency in elections next year. The killings have also raised tensions with the United States, Mexico's co-sponsor in the drug war and its top trade partner.
The two countries have accused each other of hindering progress, straining diplomatic relations to the point where the U.S. ambassador to Mexico resigned last month.
CORPSES ARRIVING DAILY
Calderon pledged Friday to bring the killers behind the mass graves to justice. Some 17 suspects have been arrested so far in connection with the murders, which are undermining the president's claims that most drug war victims are criminals.
"When all these missing people start turning up, it's just not credible to say they're all criminals. There's no question that a sizable part of them are kidnapped migrants and kidnapped Mexicans," said drug war expert Pineyro.
In Matamoros, corpses are arriving almost daily from the San Fernando graves. Martinez was awaiting the results of a DNA test after giving forensic workers a lock of his hair. Coroners will not release the body until the results are in.
His son Elvis, a truck driver who hoped to find work in construction or landscaping, had paid a migrant smuggler to get him across the border lying just beyond the city morgue.
"We're not leaving," Martinez said, "until they give us my son's body."
(Reporting by correspondents in Matamoros and Mexico City; Editing by Deborah Charles)