But didn't they make it their responsibility the minute they began screening messages with the intent of reporting crimes? Selective enforcement whether by choice or mistake isn't an option they can choose here. And criminal legalities aside, I would be more concerned about the civil litigation from the victim or victim's family. Facebook pledged to prevent crime against its users, witnessed evidence that a crime would take place, and then failed to act. Tell me no one would go after Facebook's deep pockets in this situation given they could have reasonably prevented whatever crime took place, even if it meant reporting it to the proper authorities. It may just be professional paranoia talking, but I can't see how this doesn't release them from some sort of liability in a worst-case scenario.