A look inside the mind of psychopaths to discover when common pervasive traits deviate into violence, such as grandiosity, sadism, superficial charm, manipulation, lack of empathy and having a parasitic lifestyle.

A man casually details to police how he killed his wife and later drops a bombshell about a 1988 cold case murder; a Michigan woman's bludgeoning death leads police to her fiancé, a career criminal who served time for a suspected 1,200 crimes.