Guilty Pleasures (Anita Blake Vampire Hunter Series #1) by Laurell K. Hamilton

Introducing Anita Blake, vampire hunter extraordinaire. Most people don't even bat an eye at vampires since they've been given equal rights by the Supreme Court. But Anita knows better--she's seen their victims. . . . A serial killer is murdering vampires, however, and now the most powerful vampire in town wants Anita to find the killer.