Things that go bump in the night: Here there be monsters

One city. Two killers. A serial kller who preys on adulterers. A supernatural killer who kills unknowingly once it becomes human again. The city knows bout the serial killer calling himself Sin Killer and leaving a weird poem on his victims. He is blamed for all the murders including the ones he does not commit.
Questions arise throughout the city whether Sin Killer is also capable of cannibalism since his victims are eaten and mutilated.
Poice Captain Frank Penn is under heavy fire. He knows there is more than one killer in his city and one of them is his own nephew.