pick 4 of 10 favorites to create the ultimate feast you've been dreaming of. will you choose creamy lobster mac & cheese, tender, wild-caught snow crab... crispy jumbo coconut shrimp, hey, we never said choosing was easy... this is "nightline." >> tonight, devil in disguise. just delicious. >> i got a friend request from so hurry in to create your own ultimate feast before it's gone. chris on facebook. he's the best thing that has and be the party hero. ever happened to me. get ten percent off when you order red lobster to go. >> their seemingly perfect lives but only for a limited time. shared with the world. >> my daddy is a hero. the cold and flu fightings. machine. >> cut short by chris watts, the you put in your machine. press the button to brew up powerful relief. man they trusted the most. >> how do you put someone you to defeat your toughest cold and flu symptoms fast. love into an oil tank? new theraflu powerpods. >> especially your children. press. sip. relief. >> now the parents of shannan watts speaking out for the first i'm missing out on our family outings time about the colorado killer because i can't find a bladder leakage product that fits. who murdered their pregnant everything was too loose. daughter and two grandchildren. but depend® fit-flex feels tailored to me. new body camera footage from the with a range of sizes for all body types. scene of the crime. inside his mistress' police depend® fit-flex underwear is guaranteed to be your best fit.

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watts, who murdered his entire household. now after he killed their daughter and their grandchildren, his in-laws speaking out for the first time. telling us about the family they thought was happy. and the man they thought they could trust. here's abc's amy robach. >> reporter: body camera videos. >> are you chris? >> yes. >> reporter: evidence of a hidden affair. interrogation tapes. >> you lied to everyone you talked to. >> reporter: unraveling the intricate web of lies that made up chris watts' secret life. offering clues as to why he murdered his pregnant wife shannan and their two young daughters. >> you immediately suspected chris? >> yes. >> reporter: shannan's devastated parents speaking out for the first time since their daughter's murder. >> i told the police to find his gps. because his gps is going to tell them where my family is. >> reporter: from the outside, the watts family seems perfect.

in social media videos, chris plays the part of a loving husband and doting father to bella, 4, and 3-year-old celeste, also known as ce. ddy! we're here from the boat today! >> reporter: shannan is a social media have maven and master of digital stage. >> she was fun, full of life. she did so many things. she had her hand in everything. >> love you guys, have a great day! >> reporter: just about every waking moment of shannan's life streams live over facebook. >> chris and i are sitting here waiting to board our flight to miami. we're going to toronto in june. >> if you were from the outside looking in, she seemed to have the perfect life. >> she did. >> did you believe that she was happy? >> absolutely. >> yes. >> reporter: chris is a field coordinator at a local oil company. >> i love the hat. that's our show for tonight. >> reporter: shannan loves sharing their love story, which when you can't stay up with us,

started, not surprisingly, on you can catch full episodes of facebook. >> i got a friend request from "nightline" on hulu. chris on facebook. good night, america. one thing led to another. have a great weekend. and he's the best thing that has ever happened to me. >> say hi, cece. >> hi, daddy. >> how was chris as a father, as far as you could see? >> a very loving father. as far as i knew, he loved his family. >> reporter: last june, another baby is on the way. >> i know. boy, boy, chris wants a boy. i hope it's a boy for him, it will make him happy. >> reporter: as luck would have it, it's a boy. >> she had a name for him already? >> yes. >> reporter: shannan work forth a multi-level marketing company selling vitamin-infused patches. shannan's best friend and co-worker, nicole atkinson, remembers dropping o it was aro 1:45 in the morning you dropped her off? >> roughly, yeah. >> what was the last thing you

said to her? >> if you need help in the morning, let me know. we gave each other a hug, and i watched her go into the house. >> reporter: that morning shannan watts goes offline. >> she didn't text me. which is really odd because she texted me every morning. >> reporter: nicole decides to try her in person. she knows the code to the front door. >> what happened when you get to the house? >> i couldn't get in. it was locked from the inside. and then i called chris. asked if he knew where shannan was. and he said she went on a play date. and i said, chris, her car's in the garage. how could she have gone on a play date? >> reporter: nicole becomes concerned and calls the police. >> my name's nicole and i'm calling because i'm concerned about a friend of mine. she's not answering the door. she's not responding to text messages, phone calls. there's no movement in the house whatsoever. >> reporter: as nicole impatiently waits for the cops, shannan's husband, chris watts, who's at work, calls her friend

cassie rosenberg to see what's going on. >> he called me. you need to get to the house, nikki's calling the police so they can breakdown the door. he said, no, don't call the police, i don't want to get them involved. i said, you're an idiot, you need to get to the house, something's wrong. >> reporter: frederick police officer scott kunrod races to the watts house. >> how are you guy doing? nicole? >> yes. >> reporter: this is realtime footage captured on his body camera. >> i'm going to check the back, see if i can see anything. >> reporter: after a quick check of the perimeter, chris watts finally shows up. >> scott, how are you doing? this is the only vehicle she would have? >> only one that shannan -- >> she would drive? okay. >>eporr: he to src . orter: the basement, bedrooms, bathroom.

the only signs of life? chris tells police he saw his wife early that morning before he left for work. >> last i talked to her was this morning. she said she was going to take the kids to a friend's house and that's where she was going to be. i texted her today, never heard anything. >> reporter: the house appears neat and orderly. nothing out of place or rummaged through. >> we all ran through the house kind of looking for her. >> have you checked upstairs? she's not there? >> it was odd, the things that you did see. it didn't make sense to me. >> reporter: shannan's purse and wallet on the counter. wedding ring on the night stand. unmade beds. >> does she normally make the beds, the kids' beds? >> no. >> their beds would have definitely been made? >> yes. >> and her sheets wouldn't have >> no >> tre was ithe mter

beoo >> that wasn't on there? >> none of this was on there. >> the nonfitted flat sheet was found in the garbage can. >> reporter: eventually they find her cell phone. >> her phone's here. >> does she work? >> yeah, she works from home. >> from home? >> this is her lifeline. >> reporter: the kitchen. >> do your kids take any medication? >> cece takes singulair. >> reporter: medicines, including cece's epipen. >> my daughter would never leave the house without her phone or the epipens. >> definitely an odd one. >> reporter: police get a break. in the form of the watts' next-door neighbor, nate. he's got a security camera on the front of his house. >> right there. i said, i have the video surveillance. the only thing i caught was chris backing his truck into the garage. >> chris comes to your home, along with the police, to watch that surveillance footage. >> yes, he was standing in my

he had his hands like this in the air, on his shoulders. he was really swaying back and forth. >> was he saying anything? >> no, he wasn't saying anything. -- basically -- the only time i saw him show emotion was a little bit of nervousness when he was watching that tape. >> my detective just showed up. you want to talk to him? i'm going to get his info real quick. no? >> reporter: seemingly desperate to find his family, watts turns to the media for help. >> shannan, bella, celeste. if you're out there, just come back. if somebody has her, just please bring her back. i need to see everybody. >> did he sound worried? >> no, he didn't give a

flying -- flip. i said, chris, i don't think you should do any media. i said, you're the last one to have seen them, so i don't think you should. >> yet he did. >> i thank god he did. i thank god in heaven that he didn't listen to me. >> reporter: in that interview, chris admits he and shannan had exchanged words before she disappeared. >> it wasn't like an argument. we had an emotional conversation. but i'll leave it at that. >> reporter: in the weeks before shannan went missing, she expressed great concern that her marriage was falling apart, sending chris text messages like this one. if you are done, don't love me, don't want to work this out, not happy anymore and only staying because of kids, i need you to tell me. >> i'm not just staying because of the kids, they are my life and that will not change. i'm not sure what's in my head. >> she just told me that chris said he wasn't happy anymore. and that she didn't know what

was wrong. >> reporter: shannan texting another friend. chris told me last night he's want another baby. he has changed. i don't know who he is. >> did she ever suspect another woman? >> i think that she entertained the idea, because she did get -- i don't know if she checked the bank account or got an alert on her phone. >> reporter: an alert to a credit card charge from an expensive dinner at a sports bar raises her suspicions. turns out she was right. chris was having an affair with a young, pretty brunette, nicole kessinger. she says chris told her he was separate asked was working on a divorce. >> we got along very well. what we ha it s comfortable for me. i enjoyed it, i think he did as well. >> these are photos of their time together. >> he didn't have a wedding ring, he didn't mention his kids. one day he told me he had two

kids. i thought it was kind of cute, oh, he's a dad. >> reporter: all these photos, including nude pictures, would end up in a secret app camouflaged as a calculator in chris' phone. >> my daughter, she had no clue. she was clueless. when we come back, nicole'sy missing, she's 15 weeks pregnant. >> i just realized that he was lying to me and i was like, well, if you can lie to me about this, what else are you lying to me about?

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"nightline" continues. here again, amy robach. >> as police conduct their investigation into the disappearance of shannan watts and her two little daughters --

>> right here, chris. >> reporter: her husband chris agrees to take a polygraph exam. >> did you physically cause shannan's disappearance? >> no. >> are you lying about the last time you saw shannan? >> no. >> do you knower what shannan is now? >> no. >> chris fails the test. >> so it's completely clear that you were not honest during the testing but i think you already know that. you did not pass the polygraph test. >> okay. >> okay? >> i didn't lie to you on that pal graph, i promise. >> we need to talk about what actually happened. >> reporter: he doesn't admit to a crime. instead, chris watts confesses to an affair. >> i cheated on her and i feel horrible for it. she was pregnant. >> reporter: he refuses to name his mistress. >> who is he>> i don't want to involved in this, i don't want to ruin her life. she's a wonderful person. i saw her, took my breath away. d i'd never thought in a million years that could happen. i've never felt that way about anybody, anybody in my lifetime.

>> leave her out of it, get back to your wife and daughters. where are they? >> they were at the house when i left. they were there. >> they weren't there. they didn't leave. they vanished. >> they were there -- >> the only way they could have left is in your truck. >> reporter: eventually watts asked to speak with his father, ronnie watts, who has just flown in from north carolina. >> choked both of them to death? >> i freaked out and did the same thing. >> oh my god. if she killed bella and cece, choked them to death, you lost it and choked her? that's rage. oh, son. >> reporter: it's a stunning statement. chris watts claims shannan had attacked the kids and he killed her in a fit of rage. agents re-enter the room.

they aren't buying chris' story. >> i think we're very, very close to the truth but we're not there yet. >> i'm not a monster. i didn't kill my babies. >> reporter: honing in on where the bodies are. >> whereabouts is shannan and the girls? can you mark it for me? "s" for shannan, okay. where are the girls at? >> reporter: watts marks the spots with their officials. the two girls in separate oilre shnanhaow missing the scene. >> where he pointed to where he put your daughter and your granddaughters -- >> sickening, isn't it? >> how do you react to that? >> devastated. you know? >> he is a monster. how do you -- put someone you love -- into an oil tank?

>> especially children. >> reporter: investigators recover the bodies. the little girls' autopsies contradict their dad's version of events. >> they weren't sprang angled. those girls were smothered. his statement that he had seen shannan strangle those girls all of a sudden became an enormous lie. >> this kid keeps me going. >> i knew in my heart of hearts. the friend i cared so much for would never hurt her babies. they knew from day one that that was not true. >> reporter: chris' mistress, nicole kessinger, breaks down, thinking about what he did to his two daughters. >> he's so disgusting. i am so ashamed of him and everything. and i just -- oh, those little girls -- they're so little, they're so little. why? why, why, why, why? how? i don't even understand how you

could like bring yourself to do that. somebody who's like that big. >> reporter: chris is arrested and eventually agrees to plead guilty to killing his pregnant wife and young daughters in exchange for no death penalty. at his sentencing hearing, he must listen to shannan's mother, sandra. >> we loved you like a son. we trusted you. i didn't want death for you because that's not my right. your life is between you and god. and i pray that he has mercy for you. >> reporter: through his attorney, watts issues a short apology. >> mr. watts has asked us to share this morning that he is devastated by all of this. and although he understands that words are hollow at this point, he is sincerely sorry for all of this. >> reporter: chris watts is sentenced to life in prison without the possibility of parole. but shannan's parents have one last fear. >> explain to me why frank and

sandy have filed a wrongful death lawsuit against chris watts. >> the reason that this is being done is to make sure that chris watts can't profit from his evil actions. >> we're not going to allow him to do that. >> how do you want your daughter to be remembered? how do you want the world to remember her and your granddaughters? >> she was an amazing daughter. >> bella wanted lipstick on mommy today. show your lips and cece too. now kisses. >> she wanted to soar the earth. she always said, mom, i want to leave my mark on the earth. and she did. >> reporter: sandra's unshakeable faith gives her the strength to keep alive the happy memories of shannan and her beloved granddaughters. >> oh my goodness, give me hugs. >> reporter: for "nightline," i'm amy robach in frederick, colorado. >> i love you. >> i love you. >> our thanks to a