This was not the book for me.
Although an interesting mix of paranormal and procedural crime fiction - I could not get into Mark of the Demon. There was, literally, not a single character that I actually liked. There was a lot of show-no-tell when it came to the heroine - we had to sit through her telling people that she "gave a shit" about the victims about 30 times... *groan* Not to mention she was dull as hell. Even the hero - who I can usually appreciate in any circumstance - was pretty boring.
I suppose the ending had one hell of a twist - but, frankly, I was barely paying attention by this point. The Louisiana setting nearly saved the book... but ultimately failed. Despite the constant references to the heat, bugs and Katrina - I felt like this book could have been set anywhere.
Diana Rowland is not a bad writer - but I just don't think she is a writer for me. I could, however, appreciate well the book was crafted from beginning to end. With some writers *cough*Stephenie Meyer*cough* you can tell that they have no idea where they are going - Rowland is not one of these.
Bottom line? This was not my kind of book. But if you are looking for a twist on your standard crime novel, you might as well give this a shot.