What's Happening to Mabel?

The killer knew about this location or stumbled across it as he's having to get Mabel back there. He draws her back somehow for just a second and then he immobilizes her with the two by four. The injuries where they were not reporting bruises, nothing, defensive wounds, anything except what's happening on her face. I wonder if that means that this is someone she knows from the neighborhood and he drew her back somewhere because wouldn't if you snatch someone and force them back, he doesn't have a weapon. Right.