I wonder if this crime will ever be solved, because it appears that the murderer(s) deliberately took our everyone who could provide the police with information explaining motive and identifying suspects. And even if there is anyone left alive with that information, they may be scared to talk.
There were four crime scenes. Unless the killer's a real pro, it seems pretty unlikely that he didn't leave *something* behind somewhere. Of course it'll depend on how good the investigators are around there.