I'm thinkinf of it like this, though I've no idea since I don't know who's controlling the killer and how they're going to act; the killer is a native to the town, most likely out of or still in Ouranos Academy. They are probably well aware of the time powers and such, and are killing anyone and everyone who may have a connection to the powers. A person unknowingly escapes the killer, or is taken away, and thus starts their true hunt for said killer.