KalKal
Superstar
I don't think the show would reveal the real killer this early. Its obvious they're going to at least play with the idea that its a serial killer connected to the other missing girl.So it looks like the priest is dirty as hell but I'm not convinced he's the killer.
Mare's ex may not be the killer either but his story about just wanting to help Erin doesn't pass the smell test.
Plus, they're never explained the mysterious guy with the hood that Mare saw (or thought she saw) in the first episode. (probably another red herring, though).