MONTERREY, MEXICO -- Prosecutors in the northern Mexican state of Coahuila said the remains of between 14 and 16 people, including two teenagers, were discovered in a series of clandestine graves used by drug-trafficking gangs to bury their victims.
The charred remains were found Wednesday by army soldiers in a field in the rural community of San Jose de la Rioja, outside the northern highland town of Arteaga.
After their discovery, the remains were especially wrapped for subsequent examination by forensics experts, the Coahuila state prosecutor's office said in a report Friday.
The report indicated that "the remains of two minors whose ages ranged between 15 and 18" were found at the site, adding that the precise number of bodies could not be determined because they had been charred and buried in eight graves.
Also found were 11 barrels that had been punctured by sharp objects and presumably were used by the drug traffickers to dissolve human remains in acid.
The investigators also discovered documents belonging to a student at Coahuila's Antonio Narro Autonomous Agrarian University in the name of Sergio Gabriel De Leon Castillo, a native of Chiapas; and documents in the name of Jose Luis Lozano Moreno, a native of the neighboring state of Nuevo Leon.
Coahuila state Attorney General Jesus Torres Charles said Friday that prosecutors believe the victims may have been killed in Nuevo Leon. He said authorities found cartridges for firearms of different calibers, as well as eight pairs of handcuffs, at the scene.
Armed groups linked to the drug cartels murdered around 2,700 people nationwide in 2007 and 1,500 in 2006, with the 2008 death toll soaring to 5,630, according to a tally by the Mexico City daily El Universal.
According to press reports, some 750 people have died in drug-related violence across Mexico so far this year.
Since taking office in late 2006, President Felipe Calderon has deployed federal police and soldiers across the country in a crackdown on drug gangs battling over supply routes to the United States.
But that effort has thus far been unsuccessful in stemming the violence, due partly to cartels' ability to buy off police and prosecutors.
On Thursday, assailants gunned down Ramon Jasso Rodriguez, the head of the state police homicide unit in Nuevo Leon, of the states hardest hit by the wave of violence.
He was killed a day after leading the repression of a street protest against the presence of army soldiers in the northern city of Monterrey; authorities suggest the demonstration was promoted by allies of Mexico's powerful drug mobs.