. >> reporter: overkill, said detective paul ellzey.s will be clearly apparent, detective ellzey has deep roots in old-fashioned police work. starting as a kid, then 36 years with the dallas p.d. that's over now. he's retired from the force. but he cannot get over the sight that greeted him in shelley nance's bedroom. >> this was tragic, this was horrific. >> reporter: that sight sticks with you. >> yes. very much so. >> reporter: murder, as detective ellzey knew from long experience, takes something from the investigators, too. makes them hard sometimes. but when he learned about the victim, about her decent family, her quiet modest life, her innocence, the murder of shelley nance hit him personally. >> i mean that was doin' nothin' wrong. she was not in the wrong place at the wrong time. she was not associating with somebody that she shouldn't have been associated with. the stars lined up just right that somebody, an animal, decided to take her life. >> reporter: sounds like it got to you, this one? >> well, you know, i've got two dau