Barbara Kirwin profiles her most grisly cases: the superhero-obsessed paranoid Chandran Nathan, who riddled the medical student fiance of his goddaughter with forty-one shots from an MAK-90; college student Stephanie Wernick, who calmly suffocated her newborn baby and threw it away in a dormitory trash can; Richard Winkler, who in a religious fervor disemboweled his minister with a hunting knife as he prayed on Thanksgiving morning. Were these killers...