paula plans to make sure the daughter of shauna tiaffay never forgets. >> we talk about her mom, and how much she loved her, and what we think her mom would want for her now. >> that's all for this edition of "dateline." i'm craig melvin. thank you for watching. i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." i fell to the floor. i don't remember anything. >> she's dead, she's dead. and i was so confused. i was saying what's going on? what happened? >> reporter: a small texas town. two super close friends and a summer night in the park. >> they have this lookout you

could seat harbor bridge lit up. it's really pretty when the stars are out. >> reporter: it was the next morning that they found them. >> i could see two girls laying there, it was horrifying, there was duct tape on their mouth and hands. >> reporter: a mystifying scene. >> the only thing we have -- >> reporter: dna would point one way. a bombshell message would point to another. >> i looked at the letter. >> takes a special mind that wants to do something like that. >> reporter: to crack a case this convoluted it might just take a miracle. >> that was strorld. >> extraordinary. i just couldn't believe it. welcome to "dateline." two young women were discovered in a park, bound and gagged.

both were sexually assaulted and shot in the head. one died, but the other miraculously was still alive. some wondered could a secret relationship have been the motive for murder. here's josh mankiewicz with "a texas twist." >> named for the body of christ, corpus christi sits on the texas gulf coast, and just east of the bay say park known for bird-watching. and that what this seagull was doing there when it came across something very unnatural. >> to me, it just looked like a pile of debris, to be honks. and then he looked, and he said, oh, my god, it's two bodies. >> reporter: a crime so shocking that years later, they're still talking about it. >> i can't even imagine what was in that person's mind that evoked this violence and this

rage. >> reporter: two young women, who wanted them dead and why. >> it was a true who done it type murder. >> reporter: and along with who and why was the question of why here? >> this was definitely something that we weren't used to or accustomed to in our town. >> reporter: this part of texas isn't exactly ground zero for murder. it's 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 19-year-old 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 and laughing.

>> reporter: megan olgin was mollie's older sister, just two years apart. they were, said megan fiercely competitive. >> she was really smart and i was always kind of jealous because math came easy to her. all the subjects came easy to her. >> reporter: mollie also played drums in the high school bands but her friends brooke and stephanie said what mollie really loved is cruising down the highway singing along to bands like the spice girls. that's mollie behind the wheel. >> she loved her car a lot. one night she said i'm going to name my jar jabar. after that, she called her car jabar my car. the funniest thing. >> reporter: smart, grun afunny

car owner which made her a popular teen. >> she would never leave without saying i love you and without a hug. >> reporter: and mollie's unusually large posse of friends. 18-year-old kristene chapa. >> i talked about her a lot. >> reporter: kristene lived in a neighboring town where she was earning the reputation as a softball superstar. >> kristene was a softball. she was like the comic relief in our little group of friends. >> reporter: britney said wristene's sense of humor was a perfect match for mollie's. >> kristene brought out mollie's funny side. there was never a dull moment. >> reporter: for these 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 20 elf. their destination andrews park. >> was it safe to you? >> yeah, it did. all of the parks. >> we would go at night all the time. >> reporter: before heading out, the two called britney asking if she wanted to join them. >> they asked me to go, but i had a volleyball game the next morning so i wouldn't be able to. >> reporter: it was a decision that still haunts her. >> i just know because they called me that day, i'm like, if i was there -- >> reporter: the next morning chris and stan seamour were strolling through the park. >> we started looking through for birds in general. this place was as quiet as we've ever seen it.

>> reporter: and that's when just below one of the overlooks, they made their terrible discovery. in the tall beach grass lay the bodies of two women. >> they both looked, you know, molested or mauled. >> we didn't know if they were alive or dead. we had no idea. >> reporter: the seamours ran for help. >> 911, what is your emergency? >> we've got two dead bodies down here. >> male or female? >> two females. >> reporter: first responder travis leachman had never seen anything like that. >> it was horrifying, the clothes were off both girls. there was duct tape on their hands and mouth. >> reporter: duct tape also covered their eyes and each girl had been shot in the back of the shed. >> i went and checked the pulse on the first girl and couldn't feel a pulse. >> reporter: and then something no one expected.

>> i went to reach for the second girl and that's when she started to sit up and moan. >> it looked so hopeless, and to think that one was alive was 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, the case teeming. investigators focused on one particular group. coming up -- >> sometimes, that suggests somebody who knows the victim? >> yes. >> when "dateline" continues.

feel the clarity of non-drowsy children's claritin allergy relief. the #1 pediatrician recommended non-drowsy brand. because to a kid a grassy hill is irresistible. children's claritin. feel the clarity and live claritin clear.

it wi called usaarst and the first thing they asked was 'are you ok?' they always thank you for your service, which is nice because as a spouse you serve too. we're the hayles

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 chassic and brook allstra learned about it on facebook. >> did say what it was, male or female. along those lines. >> you didn't think it would be anybody you knew? >> i didn't think it was anybody i knew. >> neither one was picking up. >> reporter: kristene's parents grace and larry chapa were worried too.

grace had been pacing the floor ever since she discovered kristene hadn't come home the night before. >> that was unusual? >> that was very unusual. >> by now, how many times did you call your daughter? >> i would say four or five times. i even said i'm going to call the police if you don't call right now. >> which is what grace did. that's when she learned that kristene had been hurt. but the officer didn't say much else. only that she needs to get to the hospital. >> he wouldn't tell you what happened? >> no, he doesn't know. >> reporter: it wasology before arriving at the hospital that the chapas learned that kristene had been shot. >> the nurse walks in and tells us, one girl died and one girl is on the second floor and we need you to identify her. >> and they don't know who died and who lived? >> no. >> it was up to the chapas to identify the survivor. >> you couldn't go. >> i couldn't do it.

>> so grace assigned her eldest daughter that grim task. >> so, the best you're going to hope here is it's your daughter. >> and she's hurt. >> she's pretty seriously hurt? >> uh-huh. >> reporter: for the chapas the wait was excruciating. and then their daughter came back down with the news, she said, mom, it's kris. >> i was there. telling her we loved her. >> how did she look? >> it was bad. it was so bad that you couldn't even -- you didn't know it was her. >> reporter: the bullet had entered the right side of kristene chapa's 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 of molliie olgi. and news of mollie's death had reached her family. >> i was in shock. i remember crying really hard. and i was throwing stuff in my room because it didn't feel real to me. >> how were your parents? >> really emotional. i'd never seen my dad cry basically. >> reporter: so did mollie's friends stephanie and brooke. >> i just remember, she's dead, she's dead. everyone was like, who's 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 police detectives roland chavez. >> mollie can't give us information and kristene is in the hospital and she can't give

us any information. >> it's not clear whether critene is going to survive? >> right. >> reporter: someone said they saw a white car speeding from the park the night of the shootings. that led no we were so chavez and the team focused on the crime scene. there was no murder weapon. they did find two spe spent.45-caliber casings. 30 miles away from where mollie and kristene were discovered. police found an empty monste gaer drink can and five e butts. didn't smoke? >> the girls did not smoke. >> reporter: chavez sent all of that for dna testing. as for the duct tape used to cover the girls' eye, chavez felt maybe that was a clue. >> sometimes that can suggest somebody who will knows the victim, doesn't want to see them? >> uh-huh. >> as far as you know, did she have any enemies? >> that's why it's so confusing.

>> everyone loved them. >> reporter: that's also why they were all so discrete when it came to kristene and mollie. friends revealed something that not many knew. >> they began to tell us they were in a relationship. >> these weren't just two friends, they were dating? >> yes. >> reporter: that had many wondering if a romance hidden from many might have been some motive for the attack. >> conceivable that this was a hate crime? >> i mean, i'd be lying if i said that thought didn't come through my mine. >> reporter: three days later, kristene chapa regained consciousness. >> we're hoping to get the ball rolling. >> reporter: providing clues about the identity of her attacker. it's a story kristene will also share with you. coming up, krtene account.

>> the first thing we asked her, of course, was did you know the person that did this? >> when "dateline" continues. after dark. digestive advantage probiotics have a strong, natural protein shell. so while other brands may have billions of probiotics, many can struggle in stomach acid. ours survive 100x better. let our strength help you stay strong. digestive advantage. available at walmart. when you're raising a child... pinch. be soft. ah. when you're doing it alone, be strong. thanks, dad. life takes softness and strength, which is why we make angel soft with a balance of both.

i thought i was managing my moderate to severe crohn's disease. then i realized something was missing... me. my symptoms were keeping me from being there. so, i talked to my doctor and learned humira is for people who still have symptoms of crohn's disease after trying other medications. and the majority of people on humira saw significant symptom relief and many achieved remission in as little as 4 weeks. humira can lower your ability to fight infections, including tuberculosis. serious, sometimes fatal infections and cancers, including lymphoma, have happened; as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening heart failure. before treatment, get tested for tb. tell your doctor if you've been to areas where certain fungal infections are common, and if you've had tb, hepatitis b, are prone to infections, or have flu-like symptoms or sores. don't start humira if you have an infection. be there for you, and them. ask your gastroenterologist about humira. with humira, remission is possible.

larry and grace chapa kept a sleepless vigil over their daughter kristene as she lay in the icu, hovering somewhere between life and death. the 18-year-old had been shot in the head and left outside for more than eight hours.

somehow she'd survived. then just days after her brain surgery, kristene again defied the odds and began to stir. >> this is an incredible little girl here, i'm telling, she is something else. >> we asked her questions she would squeeze our hand. >> is it must have been a ponderful thing to see. >> reporter: for police, the search to find the shooter was intense. detective chavez hoping that kristene now conscious would play a big part in that but kristene still could not speak. >> it was either a squeeze of the hand or the eye. >> reporter: chavez kept it simple. >> the first thing we asked her, did you know the person who did this? and she said no. >> how tall was he? >> she described him 5'8", 5'9." >> reporter: kristene helped

draw this sketch of the man. she said she smelled of garettes whi made chav think about the cigarette butts at the crime scene. he asked that the dna test on that be put on the fast track. >> one of the things that kristene said that the assailant wore gloves. under armor gloves specifically. >> she saw the logo. >> and she was a softball player, and she said under armor gloves, that's what we were looking for. >> reporter: kristene struggled to ask a few of her own. was kristene asking you about mollie? >> she did. we did not initially give her that information. >> reporter: both chavez and kristene's parents were afraid the truth about mollie would upset kristene and maybe jeopardize her recovery. >> i would just tell her, mollie

is good. >> reporter: of course, kristene persisted and eventually given decided she deserved to know mollie's fate. family and doctors assembled in kristene's room when detectives chavez revealed the truth. >> she was distraught and crying. and told me, you know, i need you to stay strong so that you can help us and we're going to catch him. and so, she did. >> reporter: as the days passed, kristene's communication skills steadily improved, enabling her to share with police more details of that horrible night. >> it was peaceful. we wanted to her her story, too. >> you look great and it's great to see you. >> thank you. >> reporter: kristene began describing her relationship with mollie. >> i met mollie at the mall. >> was there chemistry from the beginning? >> oh, there was, we were both

very sarcastic. and laughed a lot. >> reporter: six months later the two had become a serious couple then came that june night in the park. >> why did you go to the park that night? >> because, we had missed our movie. we were driving around trying to figure out what to do. >> reporter: when they got there, kristene said she and mollie walked to an overlook. >> we weren't even there five minutes and this guy walked by. i got this weird feeling. we wanted to hurry up and get out of there. next thing you know, he's right there on mollie's side with a gun. >> reporter: she said the man forced the two girls down a steep embankment and into the tall beach grass below. then she recalled the odd way she referred to them. >> he called mollie girl number one and i was girl number two. >> he referred to you in

numbers? >> yea. >> he said it would be quick and easy. i could feel my heart beating so fast. i'm like, i want my mom. that's when i was praying, please, god, don't let me die, please. >> did mollie say anything? >> we both asked each other if we were okay? that was the last thing we both asked each other. >> that's when kristene said she was raped but the ordeal wasn't over. >> he had the gun pointed at us, we made me put duct tape over mollie's mouth and eyes. and i had to do the same to myself. i was at that stage i'm going to die, this is it. and i hear the gun go off and then i went black. everything went black. >> kristene's remarkable physical recovery turned out to be the easier part. >> i come out here for the anniversary of the shooting, or

mollie's birthday. and or the day we met. >> this is not a painful place to return to? >> it's not painful. i guess i just kind of feel closer to her, i guess, because it's the last place i saw her. >> reporter: rehab helped distract kristene from her sadness, so did working with police to find mollie's killer. >> kristene was our inspiration, seeing how hard she worked made us work that much harder for her. >> reporter: it wasn't for lack of hard work, but police had to face the truth. the investigation had stalled. >> at this point, sounds like you're kind of nowhere? >> yeah. >> reporter: and then the dna tests of the cigarette butts and the drink can came back from the lab. >> and that changes everything? >> yes. coming up -- a mysterious message rocks the case. >> the letter is written from the perspective of a hitman who has been hired to kill the

surviving victim in this case, kristene chapa. >> when "dateline" continues. simparica is what kills tick and fleas, like us. kills? kills! studies show at the end of the month, it kills more ticks in less time than frontline plus and nexgard. guess we should mosey on. see ya never, roxy! use simparica with caution in dogs with a history of seizures or neurologic disorders. the most common side effects are vomiting, diarrhea, and lethargy. say goodbye to ticks and fleas... with monthly simparica chewables. i accept i don't i even accept i i used thave a higher risk of stroke due to afib, a type of irregular heartbeat not caused by a heart valve problem. but no matter where i ride, i go for my best. so if there's something better than warfarin, i'll go for that too. eliquis. eliquis reduced the risk of stroke better than warfarin, plus had less major bleeding than warfarin. eliquis had both. don't stop taking eliquis unless your doctor tells you to, as stopping increases your risk of having a stroke.

eliquis can cause serious and in rare cases fatal bleeding. don't take eliquis if you have an artificial heart valve or abnormal bleeding. while taking eliquis, you may bruise more easily... and it may take longer than usual for any bleeding to stop. seek immediate medical care for sudden signs of bleeding, like unusual bruising. eliquis may increase your bleeding risk if you take certain medicines. tell your doctor about all planned medical or dental procedures. i'm still going for my best. and for eliquis. ask your doctor about eliquis.

here's what's happened. "the new york times" is reporting that president trump was aware of the payment to stormy daniels for several months. when exactly the president learned of the payment has not been determined. the former president george h.w. bush is back at home after two weeks' stay at the hospital. the 93-year-old was hospitalized the day after the funeral of his wife barbara. >> that's what's happening, now back to "dateline." welcome back. i'm craig melvin. kristene chapa told a harrowing tale of being raped at gunpoint by a man she never met. she remembered her assailant was wearing under armor gloves. was this a detail that could

help investigators unlock the mystery. here again is josh mankiewicz with "a 2x it twist." >> day by day, inch by inch, kristene chapa walked a steady road to recover. >> i couldn't move my arm. >> you don't give up, do you? >> i don't. i try to stay motivated. >> reporter: so did detective roland chavez, he, too, was making progress. the cigarette butts and drink can collected from the crime scene had first given them the first major break in the case. >> what did the dna show? >> the dna showed it belonged to dylan staalman. >> reporter: who is dylan staalman. police learned that he lived three blocks from the crime scene. and then chavez noticed a striking resemblance to the

drawing that kristene had drawn. some quick computer searches reveal ed stallman had a criminl past. dylan stallman had just been convicted of an armed robbery in nevada. >> yeah. >> reporter: that nevada armed robbery occurred in 2010, a year and a half before the shootings. stallman and some accomplices broke into a home in a las vegas suburb and held a family hostage before robbing them and taking off. anybody get killed? >> no. >> reporter: and at the time of the shootings in 2012, dylan stallman was in the corpus christi area, awaiting sentencing for the nevada armed robbery. >> he'd been sent here to stay with a friend. >> reporter: what intrigued chavez was some unusual similarities between the nevada crime and the shooting in texas. >> we started going through the case file we started to see more

and more things that are lining up. >> for example? >> the use of numbers. >> reporter: remember, kristene said the shooter referred to her and mollie as girl one and girl two. >> did he use numbers in that other crime? >> yes, they referred to each other by number in that particular crime. >> reporter: the similarities between the two crimes didn't end there. in the nevada home invasion was the victim found? >> yes, they were. >> definitely jumped to the top. >> reporter: by that time, dylan stallman had already returned to nevada to begin serving his three-year sentence. so chavez hopped a plane to las vegas, hoping to hear what mr. stallman might reveal about his brief stay in texas. stallman admitted he was in the park the night of the shootings but he denied being anywhere near the area where the girls were found. >> he said he was never on the deck. well, we've got dna on the cigarette butts that prove otherwise. >> why lie about that unless

you're involved in the crime. >> right. definitely raised more suspicion. >> reporter: chavez told stallman police found his dna just 30 feet from where the girls were shot. that's when he says stallman's demeanor changed. >> he asked what the consequences. >> reporter: and then dylan stallman asked about a deal. >> normally, any person that's incident isn't going to ask for a deal. you're going to profess your innocence. and he wasn't. now, i'm thinking this is my guy. >> reporter: so chavez asked stallman to take a polygraph and he agreed. >> how did he do? >> he failed. >> time for handcuffs you're thinking? not quite yet. chavez could put dylan stallman at the crime scene but had no way to tie him directly to the

shootings. >> we have no gun. we have no visible minutes. the only thing we have are cigarette butts, monster can and suspicion. >> reporter: it didn't help that chavez's one eyewitness from the shootings could not identify stallman from a photo lineup. >> it was very hard because the suspects all looked the same. >> reporter: and then there was the matter of mr. stallman's height. >> he's big, what, 6'8"? >> 6'8". >> reporter: remember, kristene said the shooter was smaller than that, 5'8". >> for me, it was difficult getting over the size. to get samples anything off of duct tape, anything off the girls' clothing anything that would be able to attach dylan stallman to them. >> does that lead you anywhere? >> no, unfortunately, it didn't. >> reporter: two years passed, the case grew so cold that that

vez's chief decided to give it to a new detective, hoping he might have better luck finding the missing pieces. detective aaron vellerman had been working the case and he took the lead. >> what we first wanted to do is expand the lead of the crime scene search. there was a crucial piece of evidence which we didn't have at that point which was the murder weapon. >> reporter: he hoped the murder weapon would definitively think stallman to the shootings. >> what that turn up? >> nothing. >> and then? >> we received a phone call from investigators at the city police department. >> reporter: those investigators at the neighboring town had just been given a letter addressed to kristene chapa's father. >> what does the letter say? >> the letter is written from the perspective of a hitman who has been hired to kill the surviving victim in this case kristene chapa. >> reporter: in the letter, the

hitman even named the person who had hired him. if you're wondering, the letter does not mention dylan stallman. all of it was a twist as big as texas. coming up, the mysterious letter. could this be the smoking gun police had been looking for? >> immediately, i knew this was something very big and very important. >> when "dateline" continues. how do i check my credit score? credit karma. don't worry, it's free. credit karma. give yourself some credit. so, you guys have recently starteyes. - yes. a little less than a month. coming up on two months now, yeah... cool. so, i want to show you guys these three chevy suv's. the first one is called the trax. beautiful!

do you think it would be good for moving in together? moving in together?! ahhh! - ahhh! okay, well, this is the chevy equinox... wow. nice. perfect for when you two have your first kid. give me some time... okay, this is the traverse. for when you have your five kids, two dogs and one cat. (laughter) whoa! five? ahhh... well, no matter what stage of life you're in chevy has an suv for you. you have it all planned out, thanks. you wouldn't accept from any one else. why accept it from your allergy pills? flonase relieves your worst symptoms including nasal congestion, which most pills don't. flonase helps block 6 key inflammatory substances. most pills only block one. flonase. hello. give me an hour in tanning room 3. cheers! that's confident. but it's not kayak confident. kayak searches hundreds of travel sites to help me plan the best trip. so i'm more than confident. forgot me goggles. kayak. search one and done. ♪ he eats a bowl of hammers at every meal ♪ ♪ he holds your house in the palm of his hand ♪ ♪ he's your home and auto man

♪ big jim, he's got you covered ♪ ♪ great big jim, there ain't no other ♪ -so, this is covered, right? -yes, ma'am. take care of it for you right now. giddyup! hi! this is jamie. we need some help. you might or joints.hing for your heart... but do you take something for your brain. with an ingredient originally found in jellyfish, prevagen is the number one selling brain-health supplement in drug stores nationwide. prevagen. the name to remember. my time is thin, but so is my lawn. now there's new scotts thick 'r lawn 3-in-1 solution. with a soil improver! seed! and fertilizer to feed! ♪ ♪ now yard time is our time. this is a scotts yard. this is a story about mail now yard time is our time. and paag. and it's also a story about people. people who rely on us every day to deliver their dreams

they're handing us more than mail they're handing us their business and while we make more e-commerce deliveries to homes than anyone else in the country, we never forget... that your business is our business the united states postal service. priority: you ♪

while detective aaron vellerman continued trying to strengthen his case against dylan stallman, investigators in neighboring sinton, texas, received a mysterious letter addressed to credkristene chapa dad. >> immediately, i knew this was was something very big and important. >> reporter: he wrote the gunman had sought his services to finish the job and make the only witness to mollie's murder disappear. >> what he's saying is i was hired to kill kristene, i'm not going to do it, instead, i'm warning you. >> that's right, he's telling kristene chapa's father, i'm going to tell you who the murderer is and then you can go do something about it. >> reporter: the letter contained details police had never mentioned in public. >> that he forced the girls to

duct tape them themselves. the fact that he called them by numbers, girl number one, girl number two. >> reporter: then the biggest revelation of l. >> he said his name is cristo ball malscher from layton, utah, to be precise, just outside of salt lake city. he worked in the area as an army reservist. >> had the name cristobal mulcher crossed your desk? >> in two years, we'd never heard of that name. >> reporter: this guy was handed to you on a plate? >> yeah. >> could it be real? should police take this at face value? >> is it possible that this letter is some thinly veiled threat to kristene that, you know, you survived but we know where you live? >> yeah, the letter was meant

for her safety. we moved very quickly to make sure she was safe. that she was protected. >> and i'm okay. no one could know where i was at. only my family knew where i was at. >> reporter: with kristene in a safe place, vellerman went straight to layton, utah. he was soon sitting across from his person of interest. >> christobal mulcher said he was on a training exercise. >> not only was he not there, he was not in the country? >> yes. >> we were not able to find a connection between the cha pa family. >> and then he showed melcher the letter. and melcher was stunned but even more surprised when he saw his picture on the last page of the

letter. >> reporter: that is because melcher immediately recognized the photo. plus he said the original photograph was of two people. the missing man, he said, was his former roommate david strickland. if the snapshot was a surprise to melcher, the name david strickland was an even bigger one for detective vellerman. turns out he crossed paths with david strickland before. >> i'd interviewed david strickland in 2012 just days after the murder. >> remember that tip about a white car seen speeding in the park the night of the murder? the tipster was david strickland. >> he came in as a good samaritan wanting to provide information. >> reporter: that meant david strickland lived just blocks from the park where the shootings took place. >> and now here he is being mentioned in connection with a guy who had been mysteriously fingered for the murder? >> that's right. >> so, just like that,

basically, mr. melcher is no longer the focus of this, it's now david strickland? >> chris melcher went on to explain that he and strickland were no longer on good terms. he believes strickland had stolen several of his guns so he had strickland arrested. >> the gun robbery put a damper on their relationship. >> strickland pleaded nat guilty to the gun charge and was released soon after. the charges were still pending and vellerman wondered could writing that letter been payback for having him arrested? >> i knew there was bad blood between them, but to accuse someone of murder. >> you think the letter was written by david strickland and includes information that only what the killer would know -- >> i think the logic would be

that he had something to do with the murder. >> reporter: detective vellerman did the same, hoping this man would turn out to be the investigation's third and final person of interest. coming up, a suspect. not acting at all like you might expect. >> he was enjoying this interview. >> maybe police have the wrong guy again. >> they would point at him in court and say that's the guy that did it. >> when "dateline" continues. all month long. and it comes in an easy-to-give tasty chew. and that makes dogs and owners happy. no wonder vets love it too. reported side effects include vomiting, itching, diarrhea, lethargy and lack of appetite. see your vet for more information on flea and tick protection you and your dog will love. nexgard. the vet's #1 choice. to bring together a group of remarkable people.

to help save the universe... from paying too much on their car insurance. hey, there's cake in the breakroom... what are you doing? um...nothing? marvel studios' avengers: infinity war, in theaters april 27th. now...where were we? oikos triple zero greek non-fat yogurt gives me fifteen grams of protein and zero added sugar. whether i'm on the field or off, every decision matters... including how i fuel. oikos. fuel your hustle. proven to protect street skaters and freestylers. stops up to 97% uv. lasts through heat. through sweat. coppertone. proven to protect. the wonderful thing about polident is the fact that it's

very, very tough on bacteria, yet it's very gentle on the denture itself. polident's 4 in 1 cleaning system consists of 4 powerful ingredients that work together to deep clean your denture in hard to reach places. it kills 99.99% of odor causing bacteria and it helps to remove stains. polident should be the first choice of every person that wears a denture, to clean their denture. hnew litter?lled this of every person that wears a denture, no. nobody has! it's unscented! (vo) new tidy cats free & clean unscented. powerful odor control with activated charcoal. free of dyes. free of fragrances. tidy cats free & clean. when no scents makes sense. you wouldn't accept from any one else. why accept it from your allergy pills? flonase relieves your worst symptoms including nasal congestion, which most pills don't. flonase helps block 6 key inflammatory substances. most pills only block one.

hey, want thedone.est internet? and now, xfinity mobile is included. you can get up to five lines. you can save 400 bucks or more a year, which you can spend on a funk-tastic music video. ♪ dance party boom. ♪ simple. easy. awesome. come see how you can save $400 or more a year with xfinity mobile. plus, ask how to keep your current phone. visit your local xfinity store today.

welcome back. a mysterious letter had identified cristobal melcher as the man who shot kristene chapa and her girlfriend mollie olgin. police wanted to hear what he had to say and they're not the only one. here's josh mankiewicz with the communication of "at texas twist." >> reporter: first came dylan stallman, cleared by police and his height. then chris melcher also cleared of suspicion by geography. now, detectives veuleman was on the trail of another man. david strictland. he was a hometown boy, his dad a successful businessman.

strikeland served in the military and was now remarried. and seized at the time of his arrest on the gun theft charge. >> i'll never forget the first photograph that popped up, it was a.45-caliber pistol and an under armor glove. >> reporter: a glock .45, the kind of gun used to shoot the girls. and the under armor glove. >> i know that because i played softball and that stuck out to me right away. >> reporter: detective veuleman immediately sent strikeland's gun to be tested to see if it fired those two spent shell casings found at the crime scene. he didn't have to wait long for the results. >> what the report said said was

the two shell casings found at the scene and the two casings on the test fire were from the same gun. >> reporter: that was the missing part of the puzzle which he believes now directly linked david strickland to the shootings. >> the day i looked at that report is the day we arrested david strickland. >> reporter: the charges, aggravated assault, aggravated sexual assault and capital murder. david strickland agreed to sit down for an interview. county prosecutor sam smith watched the interview through a one-way mirror. >> he would claim to have committed the murder -- >> you're saying that you did this? -- >> and then in the next sentence with a smile on his face, saying but that's what you wanted me to say, isn't it? >> so, it's like a game?

>> very much so a game. he was enjoying this interview. >> reporter: four years after kristene chapa was raped and shot. four years after molly olgin was murdered right next to her. david strickland faced a jury of 12. were you confident? were you worried? >> of course, i was worried. i just felt horrible. i didn't know how it was going to end up coming out. >> when you saw mr. strickland for the first time. what did you think. >> i didn't know what to think. >> he wasn't the monster you imagined? >> no. he wasn't. sometimes, those are the scariest people, though. >> reporter: prosecutor smith laid out his evidence from gunshot to snapshot to mug shot. the gun. the shell casings. and the gloves. as for the letter, smith told the jury police had found remnants of it on david strickland's computer.

>> you can delete the letter off of your computer, but if you use the spell check grammar check function, that information is still stored in the computer? >> and that's what you found? >> that's what we found. >> why do you think mr. strickland wrote that letter. he had to know suspicion would boomerang on him. >> that's what most people would think. >> it's a foolish thing -- >> it's a very foolish thing to do. >> reporter: before prosecutor smith rested, he called kristene to the stand, putting her face-to-face with david strikeland. >> i want him to see me and see what he had done but he would not look at me. >> reporter: defense attorneys john gilmore and jimmy gran bury don't dispute is that kristene was a sympathetic witness. but in court, she was also

unreliable. >> she didn't know who will shot him. >> he was unable to pick him out of a lineup and say that's the guy. >> reporter: and kristene said the shooter's gun was silver. >> david's gun is a glock which is black. >> reporter: the defense argued they mishandled evidence. >> we had the documentation that the evidence was mishandled from the chief of police. chastising the officer who handled that. >> reporter: that lead detective roland chavez admits the state's ia. he's now retired. the second detective aaron veuleman was let go for sharing sensitive details of the case with someone outside of the department. strickland's attorneys concede their client may have written that letter but they argue it would only be out of revenge for having chris melcher arrested.

as for the confidential details in the letter? >> this is small town texas. there's any number of operations this could have come from. >> reporter: but what about the lab report with strickland's shell casings found at the scene? >> we had an expert say it's inclusive. there's no way to sell for sure. >> reporter: police they say should have never taken their sights off the guy. >> dylan stallman, you think that is the killer? >> better than my boy. >> this is a guy that kicked in a door with a group of people, kicked in the door and tearized terrorized a family. it takes a special mind. >> reporter: and strickland's attorney point out he had no history of violence at all. >> it was sam smith who had the

last word. dylan stallman, he told the jury, might have been under suspicion but ultimately had nothing to do with the crime. david strickland, he said, was the man holding the gun. >> shooting both of these girls for no identifiable reason at all he's certainly a psychopath. >> reporter: prosecutor smith never offered the jury a possible motive. kristene says she's sure it's about her sexual orientation. >> in the letter that she supposedly tried to send to my dad something like those [ bleep ] lesbians. >> reporter: and in his interrogation, strickland made a point of saying he had no issues with the gay community, whether or not that was the truth, prosecutors decided not to charge him with a hate crime. after five days of testimony, the jury began deliberations. it took six hours to reach a verdict. guilty.

david strickland is appealing that conviction based on the fact, his lawyer says, the evidence presented was legally insufficient to convict him. strickland was sentenced to life in prison. for mollie's family and friends, that guilty verdict, as it often does, provided hollow satisfaction. >> we're waiting for justice and then, now, it's here, but we don't get her back. >> we have had so many huge major life moments and she hasn't been there. >> what would have been our anniversary, her birthday, the anniversary of us is the hardest. >> reporter: kristene still wonders how she escaped death and why. >> i do have survivor's guilt. and hopefully it would go away in time. >> kristene would stem, why was

it me. >> i think she's still happy to live on for mollie because mollie didn't get that chance. >> that's all for this edition of "dateline." i'm craig melvin. thank you for watching. good morning, i'm dara brown in new york at msnbc headquarters 7:00 in the even, 4:00 out west. here's what's happened. when did trump know? new reporting says the president knew about the alleged hush money paid to stormy daniels months before this denial. >> did you know about the $130,000 -- >> how president trump is handling damage control following rudy giuliani's admissions to the payout. plus, back fire, giuliani's attempt to clarify the statements made expose president