Some talking heads on true crime TV and podcasts use the terms "sociopath" and "psychopath" interchangeably. But there are major, distinguishing differences. Examining the BTK case, Phelps sorts out the variables, along with the predictable and unpredictable behaviors of these killers, with a renowned expert in the field. Plus, hear exclusive audio of a notorious serial killer’s shocking confession of what it actually feels like, from the psychopath’s perspective, to kill a human being.