There is a man serving a life sentence in a Florida prison for his part in the 1989 murder of a 29-year-old pregnant woman named Donna Callahan. Two brothers were ultimately convicted for her abduction – and each of them pointed to the other as the ultimate preparator. But only one of them would go on to confess to over a dozen other murders. That man is now considered, by some, to be one of the deadliest killers on Florida’s Gulf Coast. And if his original confessions are to be believed, then not one, but two Fort Walton Beach cases could be closed. Right now, one detective is making it his mission to find out once and for all: Can he prove Mark Riebe is the serial killer everyone thinks he is? And was he–or someone else entirely–responsible for the murders of Ronda Taylor and Bonnie Ryther?
