Two mass graves, containing a total of 12 bodies, were found in the north Mexico state of Chihuahua, one of the regions worst hit by drug violence.
Seven bodies were found by the army on Friday in a grave in Guachochi, a small town located high in the Tarahumara range of the Sierra Madre. State forensic investigators were able to identify all the victims, who relatives said had been missing since August 13.
All the corpses had their hands bound behind their backs, and were buried in a pit some 50 centimeters deep. Six were killed by strangulation, and one, a female, had been shot dead.
Five human skulls were found Monday in a village close to Ciudad Juarez. They are thought to have been buried for several years.
In recent years Mexico has seen a proliferation of mass graves where victims of the drug trafficking organizations are disposed of, known in Spanish as "narcofosas" (narco-graves).
The border city of Juarez is the most dangerous city in Mexico, if not the world, with high rates of violence driven by its position as a key point for trafficking drugs into the U.S. The area around Guachochi has also been affected by drug violence; in June, two municipal police were attacked and killed while on patrol.