Mexican authorities have announced the discovery of 12 bodies in mass graves in the northern border state of Chihuahua.

The skeletal remains were found in 11 graves in the Ascensión area, located approximately 180 kilometers west of Ciudad Juárez, near the U.S. border, according to a statement from the state’s attorney general’s office.

Investigations began at the arid site on December 18, and in the following days, the search area was expanded.