Judas Island by Kathryn R. Wall
Bay Tanner's agency gets started when she, the Judge, and Erik look into the death of Erik's old friend. Before he was murdered, Gray contacted Erik to tell him that he had found the body of a recently killed man while working as an archaeologist on the islands off of South Carolina. The next day, Gray's body is found underwater, tied to his boat, his face mutilated by the boat's propeller. As Bay and Erik get closer to the truth, they find themselves uncovering secrets that have long been buried