They say as many as 122 of the victims were passengers dragged off buses at drug cartel roadblocks on the major highway to the United States.  The mass killings of civilians at isolated ranches 90 minutes south of the Texas border mark a new level of barbarity in Mexico’s four-year U.S.-backed drug war.  As forensic teams and Mexican marines dig through deeper and darker layers here, the buried secrets in San Fernando are challenging President Felipe Calderon’s assertions that his government is winning the war and is in control of Mexico’s cities and roads.  In the past four years, more than 35,000 people have been killed and thousands more have simply disappeared, since Calderon sent the military to battle Mexican organized crime with $1.6 billion in U.S. support. U.S. officials in Mexico worry that criminal gangs are taking over sections of the vital border region not by overwhelming firepower but sheer terror.  On Thursday, cartel gunmen sacked the city of Miguel Aleman, across the river from Roma, Texas, tossing grenades and burning down three car dealerships, an auto parts outlet, a furniture store and a gas station. Three buses were strafed with gunfire Saturday in separate attacks, wounding three people.  The U.S. State Department issued new warnings Friday advising Americans to defer nonessential travel to the entire border state of Tamaulipas and large swaths of Mexico because of the threat of armed robbery, carjacking, kidnapping and murder by organized crime.  In the red dirt tombs of San Fernando, almost all the bodies were stripped of identification, meaning no licenses, bus ticket stubs or photographs of loved ones, according to interviews with local and state officials, making the job of notifying next of kin especially difficult.  Forensic photographs shown to The Washington Post depict mummified bodies caked in dirt and badly decomposed, with signs of extreme cranial trauma. In the largest two graves, holding 43 and 45 bodies, the corpses were piled atop one another in a 10-foot-deep pit dug by a backhoe, that criminals filled over in the past four months.  The red nail polish on a young victim’s toe stands out in one photograph, along with her XS-size undergarments.  Officials in Tamaulipas say they have found 34 grave sites scattered in a wide arc around this farming town of 60,000, where Mexican marines last week established a military camp for ground and helicopter patrols.  Evidence suggests that the dead include Mexicans and Central American migrants traveling to the United States to work. Only a few of the exhumed bodies have been identified, including those of a local car salesman, a federal social worker and a Guatemalan immigrant.
At the largest mass grave site ever found in Mexico, authorities have recovered few bullet casings and little evidence that the dead were killed with a gun.