A woman was hogtied and disemboweled, her intestines protruding from three deep cuts on her abdomen. Attackers left her topless, dangling by her feet and hands from a bridge in the border city of Nuevo Laredo. A bloodied man next to her was hanging by his hands, his right shoulder severed so deeply the bone was visible.

Signs left near the bodies declared the pair, both apparently in their early 20s, were killed for posting denouncements of drug cartel activities on a social network.

"This is going to happen to all of those posting funny things on the Internet," one sign said. "You better (expletive) pay attention. I'm about to get you."