Blood lines (Little, Brown Book Group)

A victim killed with a single, precise stab to the heart appears at first glance to be a robbery gone wrong. A caring, upstanding social worker lost to a senseless act of violence. But for Detective Kim Stone, something doesn't add up. When a local drug addict is found murdered with an identical wound, Kim knows instinctively that she is dealing with the same killer. But with nothing to link the two victims except the cold, calculated nature of their death, this could be her most difficult case yet. Desperate to catch the twisted individual, Kim's focus on the case is threatened when she receives a chilling letter...