Death Message by Mark Billingham
My rating: 4 of 5 stars
DI Thorne really knows how to win friends and influence people: he's got a 'friend' he put away years ago who has convinced a recently released con to send Thorne photos and videos of his kills. Just what anyone wants in their cell phone inbox, right? It's not quite a mystery as to who is doing it, it's more a question of trying to catch up and unmask the other bent policeman responsible for setting Marcus up in the first place.
Thorne is so well named, always a thorn in the side of the VIPs in the force. Even when given direct instructions he often goes his own way (giving a different cell number to Marcus, knowing that the "real" one is being tracked? huh????). Luckily it seems to work out better than one might imagine - although him being the hero of the series means that it's unlikely he'll be killed halfway through a book.