All seven animals were found in a bag which suggests that perhaps they were to be discarded with the garbage. Or that they were in fact discarded with the garbage. They certainly weren't laid out in a warehouse surrounded by candles.The police, though, have no leads.
Anyway - obviously, either they were all stricken with the plague or demonic possession and their owner had to behead them to prevent the evil from seeping out into the atmosphere - sort of like how you kill vampires. That's one option. OR they all stood up in a restaurant where the ceiling fan was too low and there was some unpleasantness.
You could more or less go on forever.