A mystifying scene. The only thing we have are cigarette butts and suspicion. Dna would point one way hes like, sarge, you gotta take a look at this. A bombshell message would point another. I read the letter and immediately knew this was something very important. A twisted trail leading to sinister suspects. It takes a special kind of mind that wants to do Something Like that. To crack a case this convoluted, it might just take a miracle. That was extraordinary. I just couldnt believe it. A shocker no one would see coming not even the killer im lester holt, and this is dateline. Heres Josh Mankiewicz with a texas twist. Reporter named for the body of christ, Corpus Christi sits on the texas gulf coast. This part of the Lone Star State is sheltered from hurricanes and storms. But as it turned out, not from one unnatural disaster. To me, it just looked like a pile of debris, to be honest. And then he looked and he said, oh, my god, its two bodies. Reporter a crime so shocking that even four years later, theyre still talking about it. I cant even imagine what was in that persons mind that evoked his violence, his rage. Reporter two young women. Who wanted them dead . And why . It was a true whodunit type murder. Reporter and along with who and why was the question of why here . This was definitely something that we werent used to or accustomed to in our town. Reporter this part of texas isnt exactly ground zero for murder. Its known more for roping, riding, and friday night lights. Here, life is pretty simple, as are the values its people hold dear, like friendship, family, community. This is where 19yearold mollie olgin grew up. Tell me a little bit about what she was like. She was really funny. She had a weird sense of humor. Always smiling, laughing. Shes just a really good person. Reporter megan olgin was mollies older sister. Just two years apart, they were, says megan, fiercely competitive. She was really smart, which i was always kind of jealous because math came so easy to her. All the subjects came easy to her. She didnt even have to study, try, nothing. Reporter mollie also played drums in the high school band. But her friends, Brooke Ostrom and stephanie chasak, say that what mollie really loved was cruising down the highway singing along to bands like the spice girls. Thats mollie behind the wheel. She loved her car a lot. I remember one night she decided, im gonna name my car jabar. And after that, she called her car jabar mccar. And it was the funniest thing, for no reason. Reporter smart, funny, and a car owner, all of which made for one very popular teen. She had a lot of friends. Yes. Oh, yeah. A lot of friends. She never let anybody leave from hanging out with her without giving them a hug. And saying, i love you. Ever. Reporter which was certainly true when it came to the newest member of mollies unusually large posse of friends, 18yearold Kristene Chapa. Could you tell they really liked each other . Yeah. Yeah. Mollie talked about her a lot. Reporter kristene lived in a neighboring town where she was earning a reputation as a softball superstar. Kristene was a softball icon for this town. Reporter Brittany Selby was kristenes close friend. She was, like, the comic relief in our little group of friends. Reporter brittany says kristenes sense of humor was a Perfect Match for mollies. Mollie definitely brought out kristenes crazy side. It was never never a dull moment with those two. Reporter but for this group of girls, crazy and dull were relative terms. We were not the party kids. We never drank or anything like that. We would go to taco bell. We would go to coffee shops. And we would go to parks. Reporter which is exactly what mollie and kristene decided to do on a warm summer night back in june of 2012. Their destination, Violet Andrews park. That place seem safe to you . Yeah, it did. All the parks did. We would go at night all the time. Reporter before heading out, the two called brittany, asking if she wanted to join them. Brittany took a pass. They had asked me to go, but i had a vollyball game the next morning. So i wasnt able to. Reporter it was a decision that still haunts her. I just know because they, like you know, they called me that night. Im like if i was there reporter the next morning, chris and stan seymour were strolling through Violet Andrews park. We started looking around for birds in general. Didnt see a thing. This place was as quiet as wed ever seen it. Reporter and thats when, just below one of the overlooks, they made their terrible discovery. In the tall beach grass lay the bodies of two young women. It just looked like they had both been molested or mauled. We didnt know if they were alive or or or dead. We had no idea. Reporter the seymours ran for help. Portland 911, whats the location of your emergency . Weve got two dead bodies down here. Are they male or female . Two females. Reporter First ResponderTravis Weisman had never seen anything like it. It was horrifying. There is blood. I can see that the clothes are off both girls. There was duct tape on on their mouths, on their hands. You could see they were clearly bound. Reporter duct tape also covered their eyes. And each girl had been shot in the back of the head. I went and checked the pulse on the first girl, i could feel her body was cold and didnt feel a pulse. Reporter and then something no one expected. I went to reach for the second girl, and thats when she started to sit up and moan. It looked so hopeless. And to think that one was alive was just a miracle. Reporter which girl had survived . Could doctors keep her alive . And what story could she tell . The questions were just beginning. One victim surviving. The first surprise in a case teaming with twists. When we come back investigators focus on one particular clue. 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People say we sit the same way. laughter i decided to go on ancestry to get my dna tested so i could find out more about my heritage. And i also found that i had a sister that i didnt know about because im adopted. That was me. It was really exciting to find myself in someone else. Discover the story only your dna can tell. Order your kit now at ancestrydna. Com reporter as dawn gave way to morning on that june day in 2012, news of a double shooting in one of the parks began to slowly spread throughout the texas gulf coast. Stephanie chasak and Brooke Ostrom learned about it on facebook. Didnt say who it was. Didnt say male or female or anything along those lines. You didnt think it would be anybody you knew. I didnt think it would be anybody i knew. Reporter Brittany Selby tried to call both kristene and mollie. Neither one of them is picking up. So thats when i started to get worried. Reporter kristenes parents, grace and larry chapa, were worried, too. Grace had been pacing the floor ever since she discovered kristene hadnt come home the night before. Thats unusual. That was very unusual. By now, how many times have you called your daughter . I would say about four or five times i called her. I even told her, im gonna call the police if you dont call me right now. Reporter which is just what grace did. Thats when she learned kristene had been hurt. But the officer wouldnt say much else, only that grace needed to get to memorial hospital. He doesnt tell you what happened . No. He doesnt know what happened. Reporter it was only after arriving at the hospital that the chapas learned kristene had been shot. But they still didnt know if kristene was alive or dead. The nurse walks in and tells us one girl died and one girl is on the second floor. And we need to identify her. And they dont know who died and who lived . No. Reporter it was up to the chapas to identify the survivor. You couldnt go . I couldnt go. I couldnt do it. Reporter so grace assigned her eldest daughter that grim task. So the best youre gonna hope for here is that its your daughter. But shes already pretty seriously hurt. Shes hurt. Yes. Reporter for the chapas, the wait was excruciating. And then their daughter returned with the news they had been praying for. She comes back down. And she tells me, mom, its kris. Reporter family and friends took turns at kristenes bedside wondering if she would ever regain consciousness. I could see her little heart, you know, rise and fall. I got her hand and i was talking to her, telling her that i was there and that we loved her. Howd she look . It was bad. It was so bad that you couldnt even you didnt know it was her. Reporter the bullet had entered the right side of Kristene Chapas head and shattered, destroying some of her brain tissue. During a lengthy surgery, doctors decided not to try to retrieve the bullet fragments. But at least kristene was still alive. By now, the other victim had been identified as mollie olgin. And news of mollies death had reached her family. I was in shock. I remember crying really hard, and i was throwing stuff in my room because it just didnt seem real to me. How were your parents . Really emotional. I had never seen my dad cry. They took it really hard. Reporter so did mollies friends, stephanie and brooke. I just remember like, shes dead, shes dead. And everyones like, whos dead . And i said, mollie. Reporter over the next few days, neighbors here began asking the same question, who had pulled the trigger and why . Finding those answers fell to portland, texas, Police DetectiveRoland Chavez. Mollie cant give us any information, and kristenes in the hospital and she cant give us any information. At that point, not even clear whether kristenes gonna survive. Right . Yeah. Reporter tips were coming in. Someone said they saw a white car speeding from the park the night of the shootings. That lead nowhere. So chavez and his team focused on the crime scene. There was no murder weapon. They did find two spent. 45 caliber casings. Reporter and near an Observation Deck just thirty feet away from where mollie and kristene were discovered, police found an empty Monster Energy drink can and five cigarette butts. And the girls didnt smoke . The girls did not smoke. Reporter chavez sent all that for dna testing. As for the duct tape used to cover the girls eyes, chavez thought maybe that was itself a clue. Sometimes that can suggest somebody who knows the victim. Didnt wanna see them. Yes, uhhuh. Far as you know, either of them have any enemies . No. Thats what was so confusing. Everyone loved them, you know. Reporter and thats probably why they were all so discreet when it came to kristene and mollie. Now, as a Murder Investigation began, friends revealed something that not many knew. They began to tell us they were in a in a relationship. These werent just two friends. They were dating. Yes. Reporter that had many here wondering if a romance that was hidden from many might have in some way been a motive for the attack. Conceivable that this was some kind of hate crime . I mean, id be lying if i said that thought didnt cross through my mind. Reporter three days later came news from the hospital. Kristene chapa had regained consciousness. Were hoping now were gonna be able to really get the ball rolling. Reporter the story kristene eventually shared with police provided intriguing clues about the identity of her attacker. And its a story kristene will also share with you. Coming up kristene harrowing account. First we asked her, did you know who did this . And then the tale told by dna. That changes everything . Yes. When dateline continues. My sweethearts gone sayonara. This scarf all thats left to remem. What she washed this like a month ago the long lasting scent of gain flings we asked woman to smell two body washes andi prefer b. Favorite. B. What was a. 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Detective Roland Chavez hoped kristene, now conscious, would be playing a big part in that. But kristene still could not speak. It was either a squeeze of the hand, and then the blinking of the eyes. Reporter so chavez kept his questions simple. The first thing we asked her, of course, is did you know the person that did this . And she said, no. Reporter and how tall was he . Shed described him as about 58, 59. Reporter within the first two weeks of her recovery, kristene helped police draw this sketch of the man who shot her. She said he smelled of cigarettes, which made chavez think about those cigarette butts found at the crime scene. He asked that the dna tests on those be put on the fast track. One of the things that kristene was also able to give us was that the assailant wore gloves, and under armour gloves specifically. Reporter she saw the logo . Yes. And she was a softball player. So shes saying under armour gloves, then under armour gloves is probably exactly what were looking for. Reporter but during those sessions with kristene, chavez wasnt the only one asking questions. Kristene struggled to ask a few of her own, tough ones. Was kristene asking you about mollie . She did. We we did not initially give her any of that information. Reporter both chavez and kristenes parents were afraid that the truth about mollie would upset kristene and maybe jeopardize her recovery. I would just tell her mollies got got sent to another hospital. Reporter of course, kristene persisted. And eventually everyone decided she deserved to know mollies fate. Family and doctors assembled in kristenes room when detective chavez revealed the truth. She was distraught and crying and and i told her, you know, i just i need you to stay strong so that you can help us, and were gonna catch him. And so she did. Reporter as the days passed, kristenes communication skills steadily improved, enabling her to share with police more details of that horrible night. Its supposed to be peaceful and safe. Reporter we wanted to hear her story, too. You look great, and its great to see you. Thank you. Reporter kristene began by describing her relationship with mollie. I met mollie at the mall. Reporter was there some chemistry right from the beginning . Oh, there was. We were both very sarcastic, and we would just amuse each other and make each other laugh a lot. Reporter six months later, the two had become a serious couple. Then came that june night in the park. Whyd you go to the park that night . Well, because we had missed our movie and so we were kind of driving around and just trying to figure out what to do. Reporter when they got there, kristene said she and mollie walked to one of the overlooks. We werent even there for five minutes when we ended up seeing, like, this guy walk by. I got a this weird feeling and we wanted to hurry up and get out of there. And the next thing you know, hes right there on mollies side with a gun. Reporter she said the man then forced the two girls down a steep embankment and into the tall beach grass below. And she recalled the odd way he referred to them both. He called mollie girl number he called mollie girl number one and i was girl number two. Reporter and he referred to you that way, by numbers, all the way through it . He did. Reporter whatd you say to him . Well, once we got under the overlook, i asked him if he was gonna take us anywhere, and he just told me like, no. This will be quick and easy. I can feel, like, my heart beating so fast. Im like, man, i want my mom. And thats when im just like praying, please god. Dont dont let dont let me die. Please. Reporter mollie say anything . We both asked each other if we were okay. And that was the last thing we asked, we both asked each other. Reporter thats when kristene says she was raped. But the ordeal wasnt over. He had the gun pointed at us still, and he made me put duct take duct tape over mollies m