Authorities in the northeastern Mexican state of Coahuila announced Feb. 7 that they had recovered at least 500 sets of human remains from mass graves scattered across 11 municipalities -- mostly in the north of the state, along the Texas border. Most of the remains were bones, which had largely survived apparent attempts at incineration. Several vats used to dissolve the remains in acid were also found in the graves. The state Prosecutor General's office says it will take at least four months to ascertain the number of victims among the remains, much less identify them. 

But mothers and family members of the state's missing, organized in survivors' group Coahuila United Forces for Our Disappeared (FUUNDEC), issued a statement announcing that are breaking off dialogue with state authorities, accusing state and federal police of damaging evidence by using heavy equipment in unearthing the mass graves. 

The Coahuila finds follow similar gruesome discoveries in two other Mexican states that same week. In the central state of Morelos, four graves yielded the bodies of two men and a woman in Amacuzac municipality. In the western state of Michoacán four decapitated heads were left in the village square of Zacán, a small pueblo in Los Reyes municipality, while 19 bodies recovered from a mass grave in the town of Tingüindín.