Who hunts the Hunters?

To go back to the OP for a moment. It is a glorious idea, but I have two points you may wish to cover before starting the game. :-
1) Why do the PCs care so much?

2) How do they actually connect the incidents and track down this guy?

Now, it being WoD there a good variety of GM tools to make the unlikely happen. But those would be the big stumbling blocks I would see to running this scenario.

Kamatej:

yeah, people make the best monsters sometimes.

Very true. Think of how people are monsters to each other, just in the name of green pieces of paper? Who needs vampires when you have human trafficking?

who needs vampires when you've got sanguinarians. The freaks come out at night - and we're among them.