>> reporter: susanne, who lives in a suburb of new york city, called diana, her sister-in-law in florida. >> and i said, have you spoken with mommy this morning? she said, you know, i called her at 7:30 and i haven't heard back from her. >> reporter: now worried, susanne got in her car and drove to peggy's house. >> as i'm driving, i'm calling the house, the cell, the house, the cell. no answer. and now i'm getting panicky. i pull into her driveway, and i saw the roof of her car through the garage door. and i said, oh, this is not going to be good. >> reporter: she was right. susanne says she found peggy crumpled at the bottom of the stairs with a knife in her chest. >> and the first thought was, oh, my god. she tripped on the cat and fell and stuck herself. >> reporter: then she says she saw the blood. >> and i said, oh, my god, she must have hit her head when she fell. >> reporter: and then susanne did something that would later raise a number of questions. >> i pulled the knife.