I've written both but not together (yet.) I'm a big fan of Steve Niles' hardboiled monster-fighting PI Cal McDonald (Dial M for Monster and Savage Membrane.) Haven't read Huston's Joe Pitt novels yet but I'm curious.
Not sure exactly what you mean by "graphic books." If you mean comics, yeah Niles does comics too, but both Dial M for Monster and Savage Membrane are straight-up fiction. And if by "graphic" you mean "gory and violent" I can't think of any hardboiled/horror stuff that is more in the PG13 range.
Carole: You and Christa should both seek out the Joe Pitt novels by Charlie Huston. They are some of the finest examples of this type of genre-melding I've read in a long, long time. More so than other authors who have over twice as many titles to their credit. Enjoy!
It's what I'm writing at the moment. I like to think of it as Zombie Noir.
I would second (third, fourth and fifth) Huston's books. He is goddamn good. Disturbingly so.
Depending on what exactly you're looking for there are a lot of books like this out there. The Dresden Files comes to mind, though I've only seen one of the tv episodes. Horrible. I hear the books are much better.
Also, Clive barker did a short story in one of his Books of Blood, though the title escapes me.
Personally, I think crime and horror are a perfect match for each other.
I didn't care much for the movie. I love gore. Lots of it. But when all of the blood looks like caro and grenadine it tends to pull me out of the story. Had the same problem with Nightbreed, though having Cronenberg as the psycho killer was a nice touch.
I'm working on a short story that fits that classification, but I'm not sure if I'll continue with other horror/crime stories. I mean, I would love to, but the story would have to be there first. In this case I combined an older story with a dream I had.