Knives. Swords. Who collects that kind of stuff . Reporter there was the guy always hoping to get her attention. Trying to corner her in the hallways at school. Texting her on the phone. Weirding me out. Reporter but maybe the brutality of the crime pointed to the roommate. Something like a lover would do. Reporter revealing the coldest and most complicated of killers. You know theres evil in there. Reporter im lester holt, and this is dateline. Heres Keith Morrison with infatuation. Reporter once there was a quiet, little girl in a quiet, little town who liked to draw. She drew the butterflies that floated, quiet like her, around italy, texas. Spelled just like the country. But they pronounce it itly. She drew a butterfly in her art class when she was in elementary school. And all the little girls are like, oh, thats so good. Draw me one. Draw me one. Reporter her name was Samantha Michelle nance, but everybody called her shelley. And her mother, cynthia, loves to tell this story about her. Everybody was just so impressed with her butterfly that she said, well, i think im gonna be an artist cause i think i can do this. You know . So she just started honing her her artistic talent from that point. She would draw everything, anything, everything. She just loved to draw. And shed draw and draw and draw. Reporter shelley was different than the other girls at school. And at home, said her dad, sam. The other two girls we couldnt keep in the house. She didnt want to go out of the house. She was perfectly happy to be at home on the weekends, staying a long time by herself. Reporter which, as you can imagine, did not make her very popular in the intensely social world of growing up. But it didnt seem to matter much to shelley. What was it she said in the yearbook . They had them write a little ep log for the seniors, all the seniors. And she wrote, you laugh at me because im different. I laugh at you because youre all the same. Reporter she wasnt like you two. No. She was totally opposite. Reporter these are her sisters, shauna nance and rachel david. Yeah, i was the wild child. She got in trouble. Reporter shelley, however, did not raise hell. Not ever. Shes very artistic, smart, nonathletic. Did not like athletics. That was more me and her department. Reporter yeah. Just very shy. She was the one that would sit in her room, read a book, play video games. Never had to worry about her. She wasnt into, like, tattoos and piercing and alcohol and sex, for sure. She avoided the majority of everything that couldve got her into trouble, and i was so happy because of that. Reporter and then when shelley was a senior in the italy high school, her teacher suggested she enter an art contest sponsored by the Art Institute of dallas. And shes like, well, you know, im not that good. And the art teacher said, no, i think you are, shelley. Reporter and she won. That same piece of art they took and put in the national competition. And it won her fourth place there. So she got a total of 13,000 to a scholarship toward the Art Institute of dallas. Reporter thats quite markable. So she this is an a major talent. And she was so excited about getting to go. Reporter the Art Institute of dallas is an urban school. Everything about it and around it as different as can be from little italy, 45 miles and a whole world away. But here, finally, was a world in which shelley felt like she belonged. Just being around people that had her same objectives and her their same mindsets. And a lot of the boys which have never really paid much attention to her in high school noticed her in college because she knew her stuff. So they were quite impressed that she was so knowledgeable in her field already. Like, caught a lot of their eyes. Reporter well, maybe they were each others kind of people. Right . Yeah, yeah. Reporter they worried about her, of course. This was the first time shelley had ever been away from home. This is what she wanted to do. And she wasnt homesick. And i said okay. Reporter it was only an hours drive away if she needed them. Her first year was just fine. And so, in september 2009, when shelley was into year two, with a circle of friends, even a boyfriend, her parents felt free to set off on their first Real Adventure alone, far from home, just the two of them. A road trip to Yellowstone National park, more than 1,400 miles up the interstate from italy. Cynthia was texting that on her phone, you know, were leaving texas now. And she sent it to each one of the girls. Rachel and shauna responded almost immediately. And no no word from shelley. And we thought, well, shes probably still asleep, you know, cause she didnt have class today. So that wasnt really unusual at the time. It wasnt till later in the evening that we thought something might be wrong cause we hadnt heard from her, and that wasnt like her at all. Reporter whats that like . Its torture. She had a premonition that something was wrong. But i what would happen to shelley . She never goes anywhere. She stays in her room. She only goes out when she has to. Reporter yeah. So the next morning, when she still hadnt called, thats when we both got worried. 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 wouldnt go check on her. They said they cant leave the office alone and go check on a class. Theyll have her call us when she gets a break. As soon as she has a break, theyll have her call us. Reporter then they phoned shelleys sister shauna. I told her really, i was like, stop worrying about it. Shes 20 years old. She doesnt want to talk to her mom. You know. I really didnt 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 llas. Thats when the School Called back. When they finally sent somebody to the classroom, and she wasnt 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 shelleys roommate, Ashley Olvera. She said, i just saw her last night at the room. She was fine. Reporter but relief didnt when ashley went home, she found her. And she wasnt all right. No, she was not. Reporter the School Called shelleys parents yet again. Were on the highway and about 200 miles from our destination in the mountains. And phone reception was really bad. Reporter so, through the static, she couldnt tell. Was she hearing or imagining the words . And she said, your daughters been found in blood. And then the phone went dead and id lost reception at that point. Reporter daughters been found in blood. Yeah. I was asking him, what does that mean . But i knew what it meant. I just didnt wanna accept it. The only thing that made sense was a Sexual Assault. Thats all i could think of because she didnt have any money. She didnt have any enemies. No. That we knew of. Reporter what is that like driving through the mountains so far away and you get that call . Panic. I wanted him to stop the truck. We were in the middle of the freeway. There was no place to cross. I wanted him to cut across the median and go back. We needed to get back. Not that we could do anything, but we shouldve been there. We shouldve been there. It kind of feels like your guts were kicked out from the inside. Thats about the best description i can it it hurts your whole soul. Reporter as they raced back toward texas, cynthias cell service finally cleared. She called the police and got the confirmation. Shelley was dead. So, again, she phoned shauna. I had to tell her her little sister was dead on the phone. I needed somebody to be there, to be my be me in my place. To be, you know, there if the Police Needed to ask questions and stuff. Somebody needed to be there. So i called her. And of course, i hated to devastate her that way over the phone, but she had to know. And i just hit the floor. I couldnt stand up, couldnt do anything, couldnt talk, just shocked. Reporter did you have any idea what happened . None. I got to the scene first cause i lived closest to her. It was like a scene out of a movie. There was tape that had everything taped off. There were cops with dogs and they were searching the garbage cans. They had cops on golf carts and they were just searching all around the crime scene. I just ran towards the cops and started yelling, shelley, shelley. Reporter they wouldnt let her in, of course. But they had questions. Well, they just wanted to know, like, if i knew her boyfriend and if i knew her roommate and who could have done Something Like this to her. Reporter meanwhile, youre flying down the highway as fast as you can go. Yeah. We were trying to get back. We were still trying to put it together in our minds what happened. Who took our little girl from us . And at that time, youre so torn up that thats you dont know what to do. Reporter what happeneded to this talented, modest, innocent young woman would be all too obvious very soon. But as for who did it, and why for the case to have the twist and turns that this one did was something that i wouldnt have dreamed in 100 years. And im seasoned. Ive seen a lot of things. Reporter no kidding. But not like this. Reporter one thing the detective would see right there at the crime scene gave him the first inkling of who the killer might be. I start thinking personal. This is probably going to be somebody that she knew. Reporter and then, could the smallest of clues lead to the biggest of breaks . A little, bitty, tiny sliver of plastic about this long. I got roots and i got wings. 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Her killer stabbed her again and again and again. Over 40 times. In the back. She was stabbed in her back. She was stabbed in her neck, behind her head. I mean this was brutal and this was savage. Reporter overkill, said detective paul ellzey. As will be clearly apparent, detective ellzey has deep roots in oldfashioned police work. Starting as a kid, then 36 years with the dallas p. D. Dad was a cop. Wife and sisters, too, worked in law enforcement. Thats over now. Hes retired from the force. But he cannot get over the sight that greeted him in shelley nances 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 shouldnt 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, ive got two daughters. And yeah, its its hard. Reporter shelley died here, in the falls, a large housing complex where the Art Institute arranged for some of its students to live. Seemed like a perfectly reasonable place, looked quite safe, when we stopped by to take some pictures one sunny afternoon. About you, i wouldnt let my daughter live there. Reporter really . Absolutely not. Reporter dallas, like any big american city, suffers from its share of crime. And the falls . You go there during the daytime, it looks very nice. But at nighttime, totally different story. Reporter innocent 20yearold girl out on the street in that neighborhood at night, youd worry about her . No way would i let my daughter walk that neighborhood at night, no way. Reporter the nances didnt know any better. Little italy, after all, presents few of the issues a person can encounter in the middle of a place like dallas. Anyway, on that september day when detective ellzey arrived at the falls, he had no idea what sort of scene would confront him there. All he knew was that a female had been murdered. Im ready to go Different Directions and i have to make some assessments. When i walk in that door and i make a left hand turn and i see that girl there, then i can eliminate things relatively quickly. She still had her panties on, which generally reporter means no Sexual Assault. Exactly right. It it relieves the Sexual Assault part of it. She has a tshirt on. So im not thinkin that that its a rape. Im not thinkin that. And when i see the stab wounds in the back then i start thinkin personal. This is probably gonna be somebody that she knew. I checked the windows. I checked the door. You wanna look for forced entry. I didnt see evidence of that. Reporter so somebody she knew. And from the looks of it the wild, repeated, ferocious stabbing somebody consumed by an uncontrollable rage. But aside from all the blood, they found no useful fingerprints, and, eventually, no dna to help them either. Whoever did this had managed to erase any sign of who he or she was. Except there was one tiny bit of well, was it evidence, what was it . They found it under shelleys left wrist. A little bitty tiny sliver of plastic. About this long. And probably a quarter of an inch in width. Reporter hmm. Any idea what it was when you found it . It wasnt confirmed until after the completion of the autopsy of what the material actually was, that it was latex, a latex material. 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 shelleys roommate, Ashley Olvera, whod found shelley dead in her own bed. Thats how ashley became possible suspect number one. She wasnt sexually assaulted, shelley. That was my initial opinion. It was later confirmed. Reporter yeah. Why couldnt a woman do this . Reporter sure. Its her roommate. Theres a lot of things happen between roommates that we dont know about. So it very well could have been. Reporter sure. What happened, if anything, between these roommates was something detective ellzey was determined to find out. Even if he had to get rough. Coming up right away, he would become convinced that something just wasnt right between the two girls. What else can you say . Its weird. 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This offer ends march twentyfirst. I kept thinking i was asleep, it was a really bad dream. And this wasnt really happening. I couldnt imagine anything like that ever happening. Reporter the first stage was denial. That shelley nance, their innocent wisp of a sister, had but maybe worse, quite possibly they werent going to know who did it. The first and most obvious mystery jumped right out at the experienced eyes that cased her bloody bedroom. Shelley had been dead a while. We could tell by lookin at her that she had not been there longer than 24 hours. Reporter but this was curious. Her roommate was in the apartment for much of that 24hour period, and claimed she saw and heard nothing amiss. Like shelley, roommate Ashley Olvera was also 20 years old and from a tiny town taft, texas not far from corpus christi, on the other side of the state. Her interest at the Art Institute was animation. She was shy like shelley but more willing to be social. They took her in for questioning. Reporter what sort of state was she in . You know, she was upset. She was cry