On April 3, 2014, serial killer Tommy Lynn Sells was executed for the murder of 13-year-old Kaylene Harris.  It is believed, however, that Sells was responsible for up to as many as 70 murders across the country.  What is the nature of psychopathy?  Why do these people walk among us?  Drs. Jessica Micono and David Morelos use the case of Tommy Lynn Sells to begin a discussion on the psychopaths that both fascinate and frighten us.