I was just think maybe it was not the killer who left Faith's head at the Woodlands. What if the purple ribbon theory is true and Faith was maybe thinking she would just try to tell Bigby everything about the ribbons after that night Bigby saved her from the Woodsman in episode 1. But than maybe her "Boss" found out and used the ribbon to kill her. Than Nerissa (Or maybe one of the other girls) planted the head at the Woodlands to get Bigby to look in to it and hope that he can save them (Because Nerissa can't just straight up tell him because shes got a ribbon on too)
As for Lilly's head i do think Crane may have left it their in hopes to plant her death on the original "killer". I think Lilly's death may have been an accident maybe Crane took her ribbon off during their little reenactment of Snow's story.
So does anyone else have a theory about this?