this is "nightline." >> tonight, vanished. one family's desperate search for a missing young woman. >> i don't want to go years without knowing where my daughter is. >> reportedly last seen with a man whose ex-girlfriend also went missing without a trace a decade ago. two families united in grief and one young man at the center. plus, knockout work-out, wh kendall, and gigi are turning to boxing. we're with new york's hottest up-and-comerso see why the sweet science has become the ultimate women's sport. are you ready to punch like a girl? and best formers forever. how former first lady michelle

obama, former president george w. bush went from political adversaries, to bffs, but first the "nightline" five. n honey nut cheerios gets their delicious taste from honest ingredients. like real delicious honey and real oats. okay that's still honey. huh, there we go. we're back to honey again. who's directing this?

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both connected to the same man. now, he is under the microscope, but staying silent, as the parents of the missing women plead with him to reveal whatever he may know. my co-anchor juju chang is on the case. >> she's not the type of person to just go missing. >> she was just my best friend. >> i do want answers. i don't want to go years without knowing where my daughter is. >> reporter: it's been almost six months since jessica runnians left a party and vanished in the kansas city night. so you immediately knew something was wrong? >> yes. >> what did you tell them? >> my daughter's missing. >> reporter: jessica's suv found burned, abandoned in the woods. >> it was right here. >> reporter: all eyes on this man, kyler use. the last man he was seen with on that fateful night.

>> did you kill jessica? >> did you? >> reporter: connected to not one, but two missing women in the area. at 21, jessica is known for her easy laugh and playful spirit. >> we liked to drive around and blare music. >> reporter: the oldest of three girls. she's a role model to 14-year-old megan and 6-year-old michaela. >> i love you, jessica. >> reporter: her mother jamie holding on to the memories of their last times together. >> that's my last one of the four of us. >> reporter: that's a special picture. >> yes, it is. it shows our closeness. >> reporter: jamie letting us into their lives for her first extensive tv interview since her daughter went missing. >> this is the first time i ever talked about my daughter. i can talk about facts, anything and everything about her, but it's just the sentimental stuff, like future, past -- yeah, sorry.

>> see, it gets tough, but it's a hard situation. the family, it tears the family apart, period. everybody might seem like they're strong, but it's tough. >> reporter: jessica was working as a pastry chef at a local retirement home. >> i did it! >> jessica was going to start back to school in may. >> reporter: those dreams, sidelined. replaced with countless questions and few answers. her disappearance making local news headlines. >> they haven't found jessica. >> she's still missing at this hour. >> reporter: thursday, september 8th, jessica is at a party with friends. >> six to seven people there, sitting around, drinking beer, watching tv, just goofing off. >> reporter: she reportedly leaves with kyler used, a long-time friend of her boyfriend, kyler, a man with an alleged history of violence against women.

>> she offered to give him a ride? >> they came together. >> then what happened? >> she didn't go to work, nobody could find her. >> when did you get the feeling something was wrong? >> when she didn't show up to her doctor's appointment in the afternoon. i called her boyfriend and told him to meet me at the police station. >> reporter: hours later, they find her car, destroyed by fire in an isolated, wooded area, just off the road. >> with the burned-out vehicle, no telling what you're going to find if anything. high heat will destroy any dna for the most part. any fingerprints would probably be gone, anything like that. >> reporter: there's no sign of jessica inside. >> that was my worst fear, that she was burnt inside. >> reporter: a search party scours the woods and comes up empty. >> it's suspicious circumstances to find her vehicle burned,

unkoupped in a remote area. >> reporter: early the next morning, kyler is arrested, accused of setting her car on fire, charged with knowingly burning a vehicle. he's pleaded not guilty. denying any involvement with her disappearance to 41 action news. >> kyler, where's jessica? >> i have no idea, sir. >> reporter: kyler had a troubled childhood. court documents allege that he was physically and sexually buys abused as a child and that he drank and started doing drugs at age 12. if you could talk to him, what would you say to him? >> just tell me where my daughter is. i don't care about anything else. i just want to know. >> reporter: molly hastings is her lawyer. jessica's mother is begging him to speak out, but you've advised him not to. >> any attorney worth their salt would give him the same advice. and this is not advice to further punish or penalize jessica's family. kyler has not been charged with anything outside of knowingly burning this car, and that is,

again, a charge we've pled not guilty to, and that we intend to fight. >> reporter: kyler used is still in jail, awaiting trial for charges related to the burning of the suv. he's never been charged in her disappearance. but were there disturbing signs in his past? >> the court documents show an escalation of violence. >> any time you have domestic violence, there's an escalation. >> reporter: in 2011, an ex-girlfriend sought an order of protection, alleging he punch, clapped, and choked her, saying he threatened to kill her and her baby. but what happened to his other girlfriend ten years ago is most alarming. >> she was 17 when she went missing, kara. >> kara loved her friends, loved being around people. she always had a -- she had a smile. >> reporter: her parents say they noticed a personality change after she started dating

kyler. they say he isolated her from friends and family. >> his idea was to separate her from us, so he could have the control, the manipulation over her. >> reporter: later her family said they started noticing bruises and she told them stories indicating physical and emotional abuse. >> she said he grabbed me by the throat, slammed up into the corner of the door and said, what are you gonna do now, [ bleep ], and she said, dad, i thought he was going to kill me. >> she filed for an order of appreciation, saying he had a knif in hand and said, i'm going to slit your throat. these are the last known images of her. on may 4, 2007, she left school and disappeared. >> he's never been charged with any crime related to her disappearance. i have every expectation that had there been enough evidence against him to have charged him in that young woman's appearance, they would have.

and they haven't. and it's been ten years. >> and yet ten years later, he's still a person of interest in that case. >> i think he will be a person of interest forever, based on the fact that public opinion has already made up its mind. >> reporter: for police lieutenant brad swanson, kyler has stuck with him for nearly a decade. >> at the time of her disappearance, this was the high school. >> a decade later, kyler is distill a person of interest? >> yes, you can say that. he's been able to eliminate a lot of people, we haven't eliminated kyler. >> that doesn't make him a suspect? >> correct. >> this is where we meet once or twice a month. >> reporter: but for jamie, it's not about kyler, it's about answers, and bringing together a community of support. >> 40 of us get together, we brain storm, hit the maps, talk about the maps. >> reporter: the garage, now a make shift missing persons

headquarters. >> we took over a hundred people in the first three weeks. we cleared from the back part all the way up to the housing. >> reporter: the search is a family affair. jessica's father, john michael runions, searching with his team. jessica's grandfather is also wanting this nightmare to end. he often searches for jessica at night, driving the same route he thinks she would have taken after that party. >> the hardest problem is, there's no closure. that's the thing. everybody's looking for a little closure. jamie's pretty strong, but eventually there's a time when jamie is -- it's gonna hit her and hit her hard. >> are you afraid of what you could find? >> it will be hard. but the thing of it is, we have

found her. either way. i mean, it will be hard. but the thing of it is, is, my wish will come true, her nightmare will be over, and she will be with us, no matter what. >> reporter: a wish now shared by these two families, united in grief, still searching for answers. for "nightline," i'm juju chang in kansas city, missouri. >> our thanks to juju for that report. coming up next here, something very different. is boxing the new yoga? why more and more women are going the distance. and later, the unlikely friendship between george w. bush and michelle obama. in my asthma treatment with breo. once-daily breo prevents asthma symptoms. breo is for adults with asthma not well controlled on a long-term asthma control medicine, like an inhaled corticosteroid. breo won't replace a rescue inhaler for sudden breathing problems. breo is specifically designed to open up airways

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♪ ♪ in the old days, if you had told the woman she had the body of a boxer, it might not have gone over so well. but now that world class fashion models are gloving up, things are changing. we go toe to toe with some of new york's heaviest hitters. >> are y'all ready, new york? we go in three, we go in two, we go right now, jumping jacks, let's go! >> it's the fitness craze sweeping the nation. it makes you, like, super confident. you feel kinda invincible. >> reporter: the original work-out, once considered a man's sport, is catching on as the hottest womet figh celebrities to super models are stepping into the ring. >> it's fun. especially when you're like really pissed at someone. >> reporter: kendall jenner, adriana lima and gisele sharing

their boxing work-outs on social media. and jgigi hadid showing off her skills for reebok. new boxing studios are opening all over the country. rumble is backed by rocky himself. >> rocky's got him on the ropes! >> reporter: models like gisele and gigi, people you would think would be off doing yoga, they're boxing. why is this taking off like this? >> one, because it works. especially coupling with the strength training. >> reporter: noah neiman is the co-founder of rumble. here, as many as 60 people train at the same time. >> there's nothing like a boxer's high. it makes you feel like ali in his prime. >> reporter: he says 70% of his clients are women. >> i've learned technique, and as i'm relaxed, i still feel

invigorated and very, very powerful. >> reporter: two regulars at this studio are 24-year-old maria, and 19-year-old chase carter. both top models in new york city who say they use boxing regularly to stay in shape. what most surprised you when you started boxing? >> the strength of my core got super strong and leaned out in the middle, kind of like an hourglass. >> and everybody wants that. >> what do you think about phrases like punch like a girl? >> if we could just prove them wrong, right? >> reporter: after a quick warm-up, it's time to hit the bag. half the room starts on strength training, while the other half boxes. noah says boxing works every part of the body, but legs are the foundation. every punch starts there. the last thing we worry about is throwing our arms. we really want to generate that power from the movement of our

body. your knuckles are just an extension of your hips, your core, your legs, the most powerful parts of your body. >> reporter: all this at a time when professional women's boxing has come to the forefront. these two led the charge for the u.s. at the 2016 olympic games. mayer spends almost all of her time in the gym. >> boxing, i mean, i just switched gears. it focused me, i stopped going out, i stopped partying. i cracked down in school. >> reporter: boxing is as much a mental work-out as it is physical. >> women are invested in breaking boundaries and boxing has been, up until now, a male dominated sport. women want to push that boundary. that's a very empowering feeling and women are into empowerment. >> you were saying it makes you feel more confident. is it just the act of punching? >> i think it's the way that you hit the bag.

when you learn to hit the bag in such a way that you can hear it, it's just so satisfying. >> nearly 40 million people were practicing yoga tin the united states last year. boxing glove sales are up 130% from last year. and boxing has overtaken yoga as the top search term on the site. >> it's for your mind and body. >> it's for everything. i like to lead with the mind first, but the body comes, trust me. >> and we want that? >> yeah. ♪ ♪ >> reporter: back at rumble, 45 minutes later, the gloves come off. >> first of all, i'm absolutely drenched. you get surprised how into it you get when you're punching the bag. because when you hit the bag, you can feel how hard you're hitting. i feel kinda tough now, like i can kick some butt. but for now, i need a break. >> reporter: for "nightline," i'm diane macedo in new york. next, strange bedfellows. the unlikely friendship between

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and finally tonight, in politics, once in a while, you get bipartisanship, once in a while you get statesmanship. very rarely do you get this kind of friendship. >> reporter: these days, we are divided maybe like never before, but here's hope. w. and michelle, the buzz and woody of real life. >> she kinda likes my sense of humor, i guess. anybody who likes my sense of humor, i immediately like. and i needle her a little bit. >> reporter: is laura cool with this? >> you're closer to her than barack? >> uh. [ laughter ] well, let's put it this way, he's never given me a hug that way. when i saw her, it was a genuine expression of affection. we're fairly light hearted, and they're around serious people. we took to each other. i sat next to her at nancy

reagan's memorial. i can't remember where else i sat next to her, i probably have a few wise cracks, she seemed to like it okay. >> reporter: even a staunch socialist couldn't help chuckle at bush versus poncho at inauguration day. a 17-year gap and a political chasm. >> they're interested also in doing things with our troops, in their after life, as i call did. >> reporter: bush 43 promoting his books of paintings of post 9/11, war veterans. >> it's going to take them a while to find their footing, figure out how they're going to do what they want to do. >> reporter: recently revealed, the letter from bush 41 to bill, i am rooting for you. can we all learn a lesson from that? and this. i'm nick watt for "nightline" in los angeles. >> our thanks to nick and to you for watching abc news tonight.

we're online 24/7 at abc news.com and on our "nightline" facebook page. thank you for watching and goodnight.