Friend of the Devil by Peter Robinson
If you are unfamiliar with the series of mystery -suspense novels by Peter Robinson, you are in for a treat. There are over a dozen novels in the series, which feature Yorkshire Detective Chief Inspector Alan Banks and his colleague and sometime love interest, Det. Insp. Annie Cabbot. In his latest, Friend of the Devil, Banks and Cabbot investigate two gruesome and seemingly unrelated murders while studiously ignoring their mutual attraction.