Undone by Karin Slaughter

Dr. Sara Linton crosses paths with detectives Will Trent and Faith Mitchell while on the job in the emergency room at Grady Hospital in Atlanta. In treating a woman who was the victim of a hit and run after she was severely tortured, Sara's expertise and her background as a former coroner come in handy. With the victim near death and not able to communicate, Will and Faith are glad for any help, especially since the local police are resentful of them taking over the case (they work for the Georgia Bureau of Investigation). After Will finds a second victim, they know a serial killer is at work and wonder if they can amass enough clues to find him before he inflicts his gruesome acts on another woman. In Undone, Slaughter brings her two series together in one book successfully.