reporter: the first thing the next morning, cynthia called the art institute. to find out if shelley was in class. and actually, they well, they wouldn t go check on her. they said they can t leave the office alone and go check on a class. they ll have her call us when she gets a break. as soon as she has a break, they ll have her call us. reporter: then they phoned shelley s sister shauna. i told her really, i was like, stop worrying about it. she s 20 years old. she doesn t want to talk to her mom. you know. i really didn t think anything bad would ever happen to her, so i just kind of brushed it off. reporter: so they kept driving. by now they were almost a thousand miles from dallas. that s when the school called back. when they finally sent somebody to the classroom, and she wasn t there, well, i was ready to turn around right there cause i knew something was wrong. reporter: then relief. someone from the school ran into shelley s roommate, ashley olvera.
reporter: a a kind of material that that a pathologist would be rather familiar with doing his autopsies. it appeared to be a fragment of a disposable glove. of course they tested it to be sure it did not come from the medical examiner or any of the officers at the crime scene. and it did not. must have been left by the otherwise careful killer. but who would want to hurt her? and so horribly? the first person detective ellzey talked to was shelley s roommate, ashley olvera, who d found shelley dead in her own bed. that s how ashley became possible suspect number one. she wasn t sexually assaulted, shelley. that was my initial opinion. it was later confirmed. reporter: yeah. why couldn t a woman do this? reporter: sure. it s her roommate. there s a lot of things happen between roommates that we don t know about. so it very well could have been. reporter: sure. what happened, if anything, between these roommates was something detective ellzey was
saying, okay, well, let s say that the other person did it. nathan. nathan. let s say nathan did it. or let s say ashley did it, and and let s look at the evidence, and does that bear fruit or is that something where you look at at them, and it just it just doesn t work? because we wanted to make sure we got the right person. could you have prosecuted nathan? abs absolutely. i mean, it would ve been it would ve been an easy case. really? to say absolutely. to come in and say, he did it, he s the boyfriend, any time you have a stabbing, you immediately look to whoever that person is romantically involved with. reporter: so they called in nathan yet again tested his answers. multiple times. ashley, too? yes, yes. reporter: they finally arrived at the same conclusion the dallas police did that neither ashley nor nathan killed shelley. had to be daniel and daniel alone. but making the case in court might not be so easy. this is one of those cases
he was afraid? yes. i was like reporter: little nervous? a father to him, yes. reporter: or or the way but he reporter: but the way it was described later was more like you were a mother to him. i mean, you were well, yes, that was his own his own words. daniel worried about nathan, he said. saw early red flags in nathan s behavior toward this first girlfriend of his. nathan, he said, seemed obsessed with shelley. maybe dangerously. i started to notice that nathan had missed his classes. and finally, i talk to shelley s roommate, ashley, and what she told me shocked me because from her own words, nathan was actually stalking shelley everywhere she goes. and after shelley was murdered, he said, he saw scratches on nathan s body. which, in fact, the police had noticed, too. and then daniel added something very interesting he picked up nathan from school on thursday night, that s the day of the killing.
ashley had a key. i need to know what happened. i i have to have an explanation as to what happened. you re the only one that can tell me. i know and i m telling you the truth! ashley, i don t believe you, honey. i know. i don t believe you. i know! i don t believe you. you cut her. you stabbed her, didn t you? no, i did not. yeah, you did. i just need to know why you did it. i did not kill her. yeah, you did, i can prove you did it. something made you snap. i didn t hurt her. i m looking you straight in the eye, sir. nobody else could have did it, nobody else could have did it. nobody! this looks terrible for you. i know it does. this looks terrible, terrible, terrible for you. reporter: no, detective ellzey did not go easy on shelley s roommate. but there was a murder to solve. and the first day of an investigation is crucial. time to bring in the boyfriend. coming up shelley had been stabbed to