From The Grey House:
Most humans, like Bethany, were unaware of the creatures in the shadows. Natalia felt it best to keep Bethany and other humans unaware of the creatures. She learned herself, at too early an age, that monsters existed. Not all were non-humans like vampires or werewolves, either. Some of the worst monsters she’d met were humans. Still, the human ones could be contained in jails, prisons and hospitals. No one could contain a werewolf in jail. Not for long anyway.