After being taken into police custody, interviewed and studied, FBI profilers called him the most terrifying subject they had ever encountered. With an 'efficiency' and preternatural cunning that was unusual among even the most well known serial killers, Israel Keyes brought this monstrous modus operandi to a whole new level of planning and malevolence. What did Keyes have in common with the well documented cases of psychopaths who murdered people for their own gratification and who came...