That Ol' Black Magic. The Penumbra Papers, #1

Dead magicks in the Big Easy... New Orleans is neutral territory so when prominent members of several magical races are murdered, the FBI steps in. A human FBI agent with an X Files mentality.Handpicked to be the Preternatural Liaison Officer, Sade Marquis, along with her werewolf partner Caleb Jones, heads south to investigate. As SAC of the MAGIC Unit (Magical Activity, Grievances, and Inhuman Crimes), it's her job to deal with the monsters.
She needs to find and arrest the culprit before war breaks out among the Realms. The investigation is complicated by Roman Montagne, a gargoyle sentinel, and Sade's faerie nemesis, Ariel-aka the King's Seducer. Oh, and then there's the new dragon in town, Nikolas Constantine. Sade can't decide whether to arrest his ass or admire it. When guilt and innocence collide in the French Quarter, it will take Sade's brand of crazy to sort it all out.
Welcome to the Penumbra Papers, the exciting Urban Fantasy series from award-winning author Silver James. These "Cases from the Shadow's Edge" explore the forces of light and dark as they dance through shadows humans barely glimpsed prior to the Big Rip. Since then, all manner of preternatural magicks intermingle with humans in ways mysterious, magical and, in some cases, criminal. Much to humanity's surprise, there really are monsters under the bed and the things that go bump in the night are bigger and scarier than anyone ever imagined.