At a time when violent crime is dropping, one category of deceptively dangerous people -- serial killers -- is causing alarm from coast to coast with seemingly motiveless murders. These people are not creatures or animals who can easily be identified. Serial killers are hard to find and virtually undetectable until they start murdering the innocent. Like all evolved predators, they know how to stalk their victims by gaining their trust. "Serial killers don't wear their hearts on their sleeve. Instead, they hide behind a carefully construc ....