Mr. Devil seems to be in charge. We don't know how. Apparently, mostly through the sacristan, who initially treated him with respect. As for mysticism, the movie only shows a few otherworldly moments. These include Carlo's self-disclosing textbook, a bloody crib in the hotel hallway, and voices out of nowhere belonging to Paolino, Emilio, and the dead girl. All of this was probably the Devil's work. But the murders were very real: Emilio gnawed his sister with his fangs, Carlo shot Emilio with a slingshot. True, Carlo's father died under strange circumstances - it happened while Carlo was opening the gate for him. Since he had a gun, we can assume that there was an accidental shot. Another shot was the death of Dario's father and Dolores, who knew too much. But we don't know the details of these deaths.