Killer theory
I know alot of people think the ginger guy is the killer but i want to give a new perspective on things:
I think Crane is the killer , we find out in episode 1 that he was the guy that ran away from the headless horseman and maybe he's trying to bring him back to get his revenge on him for what he did back then. So he's killing people by cutting their head off and trying to perform some sort of ritual and that's why he leaves the heads so carefully placed on the stairs and did anyone notice that he started putting blame on snow and bigby right away and he seemed angry more then shocked maybe because the ritual failed.
Why kill faith ? well maybe he tought she wouldn't be missed when he saw her on he street he tought no one will miss a hooker and killed her.
Why kill snow? maybe when snow left bigby in the bar she overheard crane saying something that could make him guilty and killed her and decided to try his ritual once more.
Or the reason for killing them could be different.
The ginger guy(cryer) could be assiting crane in this ritual and picking crane's victims for him and getting some sort of pay check.
maybe crane doesn't know that the ginger is cryer(explained in other theorys that ginger is cryer ) so cryer is taking advatage of this and getting payed AND taking revenge on bigby at the same time. That's why cryer is always at the crime scene you see him in the scene faith was at the woodsman's place walking out of the building or so it looks like . And he's walking over to where bigby and the woodsman went after they fell of the building.also he is the taxi driver for snow and bigby when bigby goes into the bar and leaves snow with cryer and cryer might have taken her to crane.
just a theory but hey worth a shot