Hold Me Closer, Necromancer has a pretty huge body count, so it makes sense that a law enforcement official might show up at some point. So say hello to Detective Dunaway, who's pretty much your average, everyday cookie cutter cop character. His main function in the story is to add some dramatic tension by investigating Brooke's death, as well as Sam's suspicious assault by Michael the same night.
The thing that's kind of entertaining about Dunaway is that although he's thoroughly committed to upholding the law, he remains pretty cool even when pretty bizarre stuff goes down. At the end of the book, he winds up present for the graveside ceremony that reunites Brooke's head with her body—and when he calls Sam the next day, he responds to the ritual by saying, "I'm not sure what to do with the info you've given me, but I'll figure something out" (31.96). He may be baffled, but he also rolls with the punches. Good on ya, Dunaway.