While bloody death tolls and ubiquitous violence are nothing new in a country that has seen an estimated 106,000 people killed in drug violence since 2006, the disappearance of 43 college students has shaken the country and spurred widespread protests across Mexico.
A heavily redacted U.S. government indicates that officials in Washington are gravely concerned about the escalation of violence and drug trafficking in the Mexican state of Guerrero, the site of the disappearance of 43 college students last September.
The discovery of mass graves in the state raises "alarming questions about the widespread nature of cartel violence in the region and the level of government complicity," states a document written by a human rights working group under the U.S. Northern Command (Northcom) and released by George Washington University’s National Security Archive.
The note circulated around government agencies following the disappearance of the students from the Ayotzinapa Rural Normal School, a rural teacher training college, and expresses added concern by the fact that none of the bodies in a slew of mass graves belonged to the students.
The 43 students disappeared after a clash with police in the town of Iguala, about 100 miles southwest of Mexico City, and were turned over to a local drug gang, Guerreros Unidos, who later burned the bodies, according to the federal government's version of events.
The crime has shaken the country and drawn international criticism and protests over the involvement of municipal officials and police in the disappearance of the students.
Along with the reference to Guerrero, the Northcom note also mentions an incident that took place in Tlatlaya, 150 miles south of Mexico City.
A Mexican investigation gave a gruesome version of what happened in the June 30 mass killing of 22 alleged gang members, contradicting the army, which said all died in a fierce gun battle after soldiers came under fire in the town of San Pedro Limón. Three of the victims were teenagers.
Calling it "one of the most serious human rights violations that can be committed," an investigation headed by Raúl Plascencia issued a report challenging all official versions to date and called on prosecutors to investigate the cover up. It said the crime scene was altered to mimic the army's official version of a shootout.
"The scene was so altered that some bodies were moved, and weapons were placed on all the dead bodies lying in the dirt," Plascencia wrote.
Someone had twisted the head of one suspect until his neck broke. Four other bodies had marks of having been beaten with blunt objects before they were killed. Bullet marks and other evidence indicated that seven others among the dead were lined up near the walls of the warehouse and shot "when they were disarmed and were not resisting," Plascencia said.
The report says survivors of the shooting were tortured and threatened with sexual violence to support the army's version of events, and prosecutors in Mexico state altered autopsies.
The Associated Press contributed to this report.