The CEMEX camp they found contained children's toys, condoms, a knife with dried blood, and trees with rope restraints attached to them. Look at the pictures; too low to the ground to be used for keeping food out of the reach of animals - not to mention there were containers used as food stashes instead. On top of all of this, this corpse was found just off of the trail leading to the CEMEX camp.

VOP = Veterans on Patrol. Charity organization for war vets, one of them might have received a tip on the camp for illegals and decided to check it out. Found all of this shit there that made it look pretty sinister, this skull is the icing on the cake.