very thing that freed him, reasonable doubt, could also shadow conrad truman for the rest of his life. that's all for this edition of "dateline." i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." marie was a very loving person. she had a heart of gold. >> reporter: what happened to this woman? >> my job is to be a truth teller and seek out the truth. i wanted to solve it! >> reporter: her case was a mystery for years. the mom with the tender heart and tough-as-nails career. >> she was part of the sheriff's department. her ultimate goal was to try to get into the fbi. >> reporter: she'd found a new sense of purpose in the church. her pastor and his wife, like family.

>> they had taken her in, they were helping her out. >> i was like, i'm proud of you, you're finding god. >> reporter: then, one baffling text. and she was gone. >> i go, "i know i probably i watch lot of "law and order," but i just have this gut feeling." >> because i was a mom, i just knew she didn't leave on her own. there was no way she left that baby. >> reporter: two moms at opposite ends of a mystery. could one get justice for the other? >> this case for sure was an investigator's worst nightmare. >> reporter: soon, clues to a hidden life! >> a very, very amorous romantic, wild relationship. >> it was lustful. oh my goodness! >> reporter: there were secrets here. deadly ones. >> it hit me hard. i'm like "no, no, no, no, no!" >> a come to jesus moment? >> it was, yeah. >> i was scared to death!

>> hello and welcome to "dateline." marie carlson was a force of nature. enthusiastic, spirited, and beautiful. behind the radiant glow she hid a darkness. for a while, marie drift. then a pastor and his wife welcomed her into their lives. it was a spiritual awakening which made marie's sudden disappearance all the more mysterious. it would take a detective with a special bond and some divine intervention to find out what happened to marie. here's keith morrison with "secrets on the emerald coast." >> reporter: how do you catch a dancing sprite? do you put her in a bottle? can you package the joy she brings? can you keep it when she goes? >> she was like a gravitational pull. >> reporter: her name was marie. marie carlson. >> she was magnetic. >> reporter: when she was happy she could make the whole world sing. >> live life to the fullest, is

what marie would tell me. you know, you might not have tomorrow. >> reporter: and so she offered herself, her goodness. gave her vulnerable heart, and stored her secrets until, well, what happened. but she was always that way -- marie, from the time of the very first secret in her life. she was born in the philippines to a single mother, then taken in by the family of an american serviceman. and it was years later when she learned that kind serviceman was actually her father. which meant that esta bridges, the best friend she grew up with, was also her sister. >> what was that like to find that out that she was actually your sister. >> i was happy. i was really happy 'cause i always thought she was, since we were little girls. >> reporter: when they got older esta and marie moved to florida and lived together. the location ideal. >> we chose an apartment that was behind a karaoke club, so that we could -- >> perfect. >> just go there all the time.

we were like stars. >> reporter: and she wore pink. always pink. >> it was her personality. it's full of life. >> reporter: and always trying to perk up everyone else up with her favorite word, beautiful. >> i was, like, "oh, she's so beautiful. you know, i wanna be like her." but she always used to tell me, "no, you are beautiful." >> she loved that word. >> reporter: kay barber was like a mother to marie. hers is the second family to take marie in when she was 18 and struggling. >> marie's nickname that i gave her was rosy because she was always just, you know, peachy and rosy and happy. >> reporter: like she was when she met jeff carlson, and he fell hard. >> and it was like instant. >> reporter: so they married. and they had a daughter named paris. and thought their life together would be grand. marie got a college degree in criminal justice, became a deputy sheriff.

>> her ultimate goal was to try to get into the f.b.i. >> reporter: but then, for all the love between them, there were issues. jeff learned there were more secrets. that as a girl, marie had been sexually assaulted, and sometimes her love and joy were chased into a darker place. >> the biggest issue was she didn't love herself. >> reporter: they tried, but the marriage didn't last. and after that, marie drifted a little. jobs fell through. she had to move frequently. jeff suggested paris, then three, would have a more stable life with him. >> she fought it initially, but she agreed that it was probably for the best. so, paris was with me. >> reporter: though she saw paris often, and called all the time. and then? marie finally found what her vulnerable loving soul seemed to need. >> i was actually happy for her

because she found god. >> reporter: marie had found a spiritual home at the calvary emerald coast church. it was hardly a fancy cathedral. place was in a strip mall. but fancy wasn't the point. salvation was. here, finally, marie felt right. >> and jesus is saying "you know what, you're missing him." >> reporter: the pastor was a charismatic man named james flanders who preached the bible, four square. preached in jeans and sneakers. live streamed and youtubed his sermons. >> it was a very happening place. >> reporter: jason anderson was the youth pastor. >> didn't fall asleep listening to his sermons. >> reporter: but more than that, the pastor and his wife, james and tanya flanders, were known for their big hearts, their charity. and that's when, for a third time, a family took in marie. >> she's saying that she was there until she got on her feet. >> reporter: but a whole year went by, and then what was coming couldn't be hidden. the story floating around, there had been an abusive boyfriend who abandoned her and left her

pregnant. and in july, 2011 marie gave birth to a baby girl and named her grace. the pastor and his wife took care of both of them. >> it was explained to me that they were helping her out. she was down on her luck. >> reporter: she was, by all appearances saved spiritually by faith and practically by the pastor and his wife. so, imagine the surprise when a strange group text message popped up on the phones of her family and her friends. >> can you still remember the words of that mass text? >> she said that yesterday she left ft. walton beach to do something that she always wanted to do. she didn't want us to try to stop her. and -- the -- her last words was, "i love and appreciate you all." >> reporter: but the biggest surprise -- marie did not take her three month old baby.

she left grace behind with the pastor and his wife. and right away her sister esta sensed that something wasn't right. she called her family. >> i go, "i know i probably watch a lot of "law & order," but can you find out what's going on? because i have this really gut feeling." she's like, "oh, you watch too many of those kinda shows." i'm like, "no, this is different." >> reporter: it was the fall of 2011, the very same time that a detective named nesli suhi-moore became a mother. a fact which, as you will see, may have made all the difference. >> you get a better understanding of what it's like to -- to love somebody to the end of the world and back. >> reporter: it was almost like fate intended to tie these two together in a mystery of love, and lies, and loss. where had marie carlson gone? when we come back. >> the investigators said "we're gonna open a case. which surprised me. >> where had she gone?

>> the antennas must have gone up? >> the antennas did go up. >> i just knew she didn't leave on her own. >> there was no way she left that baby. each day justin chooses to walk. at work... and after work. he does it all with dr. scholl's. only dr. scholl's has massaging gel insoles that provide all-day comfort. to keep him feeling more energized. dr. scholl's. born to move. my copd medicine... ...that's why i've got the power of 1 2 3 medicines with trelegy. the only fda-approved 3-in-1 copd treatment . ♪trelegy. ♪the power of 1-2-3. ♪trelegy 1-2-3 trelegy. with trelegy and the power of 1 2 3, i'm breathing better. trelegy works 3 ways to... ...open airways,... ...keep them open... ...and reduce inflammation... ...for 24 hours of better breathing. trelegy won't replace a rescue inhaler for sudden breathing problems. trelegy is not for asthma. tell your doctor if you have

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each day justin at work... walk. and after work. he does it all with dr. scholl's. only dr. scholl's has massaging gel insoles that provide all-day comfort. to keep him feeling more energized. dr. scholl's. born to move. reporter: marie carlson had notified family and friends she was leaving fort walton beach and nobody could figure out why or where she went. and this was very strange -- she left her three month old baby in the care of her pastor, james flanders and his wife tayna and not her family. not the woman she looked to as a mother figure, kay barber. >> it was heartbreaking.

it was heartbreaking. it was heartbreaking. >> reporter: marie's ex-husband jeff carlson got the text too. >> it didn't make sense to him that she left without calling her 7-year-old daughter paris. >> reporter: kay called jeff and said he should file a report. >> and she said, "i -- i don't know what's going on, but i think something happened." and i said, "yeah, i agree with you." >> reporter: and then jeff called the okaloosa county sheriff's office to report marie missing. >> the investigators said, "we're gonna open a case, an investigation on this." which surprised me because she's an adult. she could've just left. >> reporter: because marie was advent rouse -- adventure us on. she liked to travel. and when the mood struck her, sometimes she just took off for a few days on some whim. but -- something seemed different this time. >> reporter: she would've never have left without talking to me about it and talking to paris. she'd been gone a week when the sheriff asked detective keith

matz to look into it. that text message. something off, said her family. >> this doesn't sound like marie. >> reporter: huh, so when you got that one -- the antenna must have gone up, huh? >> the antennas did go up. >> reporter: detective nesli suhi-moore didn't hear about the case then because -- >> i was on leave. >> reporter: on maternity leave. >> correct. so -- and i came back, two weeks after she was initially reported missing. >> reporter: and that's when nesli heard from other detectives about the case keith was working on. >> poor keith had no idea that i was gonna come bully my way into that investigation. >> reporter: and why did you wanna bully your way into the investigation? >> i think the connection of just having a child -- i just knew that she didn't leave on her own. >> reporter: so here they were. partners. the young detective who happened to be a brand new mother. and the veteran who'd seen just about everything. and who soon learned from friends and family that marie was deeply attached to both her daughters. >> she had a heart of gold and

loved her paris more than anything in the world. >> reporter: but what happened in her life? and how did she end up with another baby? from esta the detectives learned about the divorce and how marie had lost her job, and how the pastor and his wife offered her a place to stay. but the questions about baby grace? esta said her relationship with marie was always supportive, and not judgmental. and when marie didn't tell her who the father was, she didn't push the subject. >> i've never questioned her because marie will tell me in her own time if she wants to tell me. i've learned with my sister i never pry. >> reporter: but that was the job of the detectives, nesli and keith, to pry and hopefully, find marie. and one of their first calls was on her church pastor, james flanders, and his wife. impressive guy, they discovered. james flanders, what was he like? >> very charismatic -- i would say he would good at his job. >> reporter: wonder what it would be like to listen to him

preach. >> you can youtube him. [ laughter ] >> reporter: yes, you can -- >> we all, at times, forget the promises of god's word. >> reporter: the pastor grew the calvary emerald coast church from scratch, spread it through youtube, and by the time marie began attending, every service filled up. >> they were a tight-knit family, that church. >> reporter: and now, with marie gone, they were caring for little grace. so did the flanders have any idea what happened to marie? perhaps they knew who the father was, and where that abusive boyfriend might be found -- and, oh yes, there was a story, all right. >> reporter: coming up -- >> questions mount and time was running out. was time running out, too? >> there was nothing to search. it was clean. this case for sure was an investigator's worst nightmare.

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>> reporter: the calvary emerald coast church of fort walton beach, florida was far more than just a place to gather on a sunday morning. led by pastor james flanders and his wife tanya, this place was a beacon of charity too. the pastor and his church sacrificed their own needs to send money to the victims of katrina. and when marie carlson needed

help they took her in, too. >> it's what pastors do for their congregation. >> reporter: but now? >> i'm left with -- a missing person who's just vanished off this earth. >> reporter: a week and a half after marie vanished, or drove away, or whatever she did, the detectives went calling on the flanders who said they fully expected marie would return -- soon. this was not the first time she took spur of the moments trips, they said. >> never to the point where she had to be reported to law enforcement missing, though. she came back. >> reporter: although the flanders told the detectives, they were quite worried about marie's state of mind. >> they noticed a downward spiral -- >> reporter: that she was going into a depression or something? >> she might be going into a depression state, yes. >> reporter: thing was, said the pastor and his wife, marie could have wild mood swings, and they knew she had a diagnosed mood disorder. >> reporter: did they tell you that she was bipolar?

>> yes, told me she was bipolar. she -- had been taking medication and was off of her medication, probably due because of her giving birth to the child. >> reporter: but there was another prescription bottle too. >> and then they also showed us a bottle that was empty, you know, that maybe alluding to the fact that she had taken medication and was gonna use it to hurt herself. >> reporter: the day she left? james told the detectives he was so worried about her state of mind that he stayed home from work to keep an eye on her. >> james says that she was acting up. and he didn't want marie take the baby. >> reporter: he was afraid the baby might be harmed or something. >> right. >> reporter: then late that afternoon, said pastor james, marie said she was tired, went to lie down, and tanya took the baby out shopping so marie could rest. the pastor said he waited around for a bit, talked to her briefly when she woke up and then went out for a run. and when he returned -- marie and her white mazda pickup truck were gone. strangely, the flanders said,

marie had packed her bags, but didn't take them. >> why would she take off and not take her bags with her? >> reporter: anyway, said the flanders, when she didn't come back that day or the next, they drove around town looking for her. went to the airport. maybe she'd parked her car there and flown away. >> reporter: did they find it? >> they did. james says that he finds it in long-term parking. >> reporter: at least part of the mystery was solved, said the pastor. she must have flown off to visit someone. they took her pickup home. so the mazda -- what did you do about that car when you got your hands on it? >> we searched it. but it was -- you know there was nothing to search. it was clean. >> reporter: they went to the airport. >> we checked the airlines. there's nothing. she didn't fly out. >> reporter: so why would marie's car be at the airport if she hadn't flown out of there? of course she could have been trying to hide her tracks from snoopy friends and family.

or what if someone else took the car to the airport, someone who wanted to make it look like she'd left town. rather fishy. then the detectives had an idea. you know the machine that spits out tickets when you enter an airport parking lot? that very ticket goes back to the toll both when you leave. >> keith and i went to the little toll booth where you give the -- your ticket. >> reporter: maybe, thought the detectives, the parking ticket for marie's mazda would tell them not just when it was dropped off but, a more important question, by whom? >> we were thinking let's get a thumbprint, or a fingerprint on one and went through every single one of them until we found the one that marie's car had received. >> reporter: and yes, they got a print. but no, it wasn't clear enough to tell whose it was. then another thought -- >> hey, let's go pull surveillance video. and of course -- >> reporter: you looked at all

of it. >> well, no. the video didn't wor -- it wasn't working. >> reporter: oh. >> -- during the time that we needed. this case, for sure, was an investigator's worst nightmare. >> reporter: dead ends everywhere. >> yes. >> reporter: and weeks went by. no sign of marie anywhere. time to embrace the thought they'd frankly, had all along. and it wasn't a good one. >> keith and i both no longer believed we had a missing person. we believed we were dealing with a homicide investigation. but what's the hardest homicide investigation you can be given? one without a body. >> reporter: yeah. >> and we didn't have marie. >> reporter: coming up, the startling secret that marie kept from just about everyone. >> i went up and i put my hand on her stomach and i said "what's going on with this?" i had a heart problem.

i was told to begin my aspirin regimen, and i just didn't listen. until i almost lost my life. my doctors again ordered me to take aspirin, and i do. be sure to talk to your doctor before you begin an aspirin regimen. listen to the doctor. take it seriously.

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people. the twister touching down hit a mobile home park and a hotel. search and rescue teams are out searching fthe ruins right new. we'll keep you posted. and residents of ft. smith, arkansas, are preparing for historic levels of flooding. floodwaters are expected to reach 41 feet breaking the previous record of 38 feet set in 1945. now back to "dateline." welcome back. marley carlson had disappeared without a trace. she hadn't taken any extra clothes or her mystery, her car was at the airport but she never got on a plane. was she depressed? that's what the pastor and his wife she'd been living with told investigators. short on clues, detectives thought they knew one thing -- marie didn't just vanish. and now the missing persons case it hit and runned into a mrpd

investigation -- had turned into a murder investigation. here's keith morrison with "secrets on the emerald coast." reporter: what a nest of puzzles. what happened to marie carlson? where did she go? or did she go anywhere? and what about grace, the baby she'd left behind? who, for example, was the father? churches tend to be beehives of gossip, so the detectives asked around. >> she had a boyfriend, was involved in an abusive relationship, she was beat up. >> reporter: this is a member of the cavalry emerald coast church. >> she found out she was pregnant. and she didn't want to go back to the guy, and didn't want to keep the child. >> reporter: in other words, she was going to have an abortion. but pastor flanders and his wife had strong views about abortion. and when they discovered her situation, they offered to help solve her dilemma. >> they were gonna adopt the baby. >> reporter: the flanders' had an older daughter, always wanted another child. but one miscarriage after

another -- and so, as this church elder told the detectives, the pastor and his wife came to an arrangement with marie. >> she would stay three months to nurse the baby and at the end of three months, the plan all along was that she would leave. that was my understanding from before the baby was born. >> with the baby? >> no, the baby was a gift for the flanders. >> reporter: a gift? maybe. it was just like marie to be generous toward the couple who'd been so good to her. but to skeptical detectives, especially this brand new mother, something about the story didn't sound quite right. the father, for example. in fact, the alleged abusive guy didn't seem to exist. but then they talked to ex-husband jeff. and the story he heard? completely different. and it came directly from marie when she came to visit jeff shortly after she got pregnant. >> i put my hand on her stomach. and i said, "what's -- what's going on with this?"

and she wasn't really showing. and her story at that time was, "well, i'm just being a surrogate for james and tanya. so we did basically the -- a type of artificial insemination." >> reporter: well, well, well, the pastor was the sperm donor. in this new story, marie's gift was to be the pastor's artificially inseminated surrogate. but why the conflicting stories? to find out, the detectives consulted three special church ladies, tanya flanders' closest confidants. >> did you have a name for this group? >> we called them the inner circle. >> reporter: and the inner circle said yes, tanya told them. but swore them to secrecy. but then, tanya gave up a little more. the method was very home-made. >> i remember them saying, "oh, it was with the -- turkey thingy." >> it was with, like, a turkey baster? >> yeah, if somebody -- yeah, if somebody asked. >> so now she's gotta -- now she's got a secret.

>> yeah, at that point. >> reporter: wait, at that point? yes. because tanya just couldn't leave it there. the next time, she admitted something very, very shocking. >> and tanya said, "well, we did it the old-fashioned way." >> reporter: james and marie had sex. which tanya told the ladies was okay with her. and as months passed and marie started showing, there was a baby shower. but oh, no. not for marie. this baby shower was for tanya. she put a balloon under her shirt for a funny photo with marie. but something here didn't seem quite right. the inner circle had to keep their secret. if the story got out? it could threaten everything she and the pastor had built. >> and as it got more and more and more into weird stuff, it was just that the stakes got higher. right? >> that's right. imagine the secrecy that the inner circle, that tanya actually told the truth to, that it's james' baby.

>> reporter: but no room for secrets in an official investigation. the detectives invited james and tanya to voluntarily come in for a chat. but only tanya showed up. and here in this little room at the sheriff's office, she let it all come out. about that night of sake and sex, when grace was conceived. >> yeah. yeah. he had a little bit too. >> you were the only one that was sober? >> but, yes, i was there. >> reporter: yes. in the room. but of course she was, said tanya. and almost casually, she revealed the heresy that, should it ever become public, would surely ruin them. >> marie was gonna move in and she was gonna be number two. >> a plural wife. >> yes. >> or whatever you call them. >> a sister wife, i think. >> reporter: it was, in short, polygamy. or their home-grown version of it. tanya told detectives she understood the bargain very well. >> i've always seen a relationship as it's -- it's

not -- sex is not a relationship. a relationship is two people coming together. and sex is just a bonus. >> reporter: a very secret bonus, of course, kept from almost everyone. but inside the bubble of their relationship, tanya said, they were happy. >> she goes, "you know what? i am so glad that you're gonna be raising grace." she said, "and i am so glad that i'm gonna be able to be here to do that with you." and i thought, "god, you know, how cool is that?" >> reporter: but then, then marie gave birth. and it wasn't cool for marie. not anymore. and certainly not adoption. >> every time we started to broach the subject with her, she did get withdrawn. >> reporter: so maybe tanya wouldn't get baby grace. maybe marie wanted it all, the baby and james, all for herself. that's what this member of the inner circle believed. >> but i -- did i hear that from

marie, that marie wanted james? >> reporter: did tanya strike back somehow? fight for her marriage by getting rid of marie? listen to how church members quoted tanya's words. >> she basically was like, "james would never be able to do that, but i could." >> shockers? >> yeah. >> i told him, you're not capable of killing her." but tanya leans over and goes, "well he couldn't, but i could." >> so wouldn't that lead you to, like a bloodhound, direct to tanya? she certainly would have a motive. >> she would. >> reporter: tanya, now the only mother figure in grace's life. did she know more than she was saying? did she do something? >> did someone in the church have a confession to make? coming up, a confrontation in the congregation. >> this is a, forgive my saying, a come to jesus moment? >> it was the hardest thing i ever had to do. >> reporter: and divine intervention? a sudden, earth-shaking tip.

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[chanting] it's not just easy. it's geico easy. oh, duncan. stay up. no sleepies. just saying you need to really learn to think different. >> reporter: an attentive churchgoer might have noticed the intrusion of an odd idea in one of the sermons of pastor

james flanders. >> what do you think we'd experience? >> reporter: when he mentioned a couple of verses in the old testament that seemed to approve, somehow, of polygamy. >> he wanted to justify his relationship to everybody else through a biblical sense. >> reporter: so he went to the old testament and -- and pulled up those few lines that suggest polygamy. >> that's correct. >> reporter: a trial balloon? if it was, it quickly if it was, it quickly imploded. and the very practical polygamy in the home of the pastor stayed carefully under wraps. >> reporter: so if the news got out to the rest of the church -- did tanya worry at what might happen there? >> that's what she was covering up. she had to protect james and protect their -- that was their world. >> reporter: did she do something to marie, to protect james? two months after marie disappeared the detectives got permission to look at the cell phone records of all three of them. would they prove tanya was with marie when she vanished and thus maybe did something to her? >> the cell phone tower information put her away from

the area. >> reporter: no. nowhere near marie. so then they checked the cell towers for james's phone, and what do you know. when marie sent that mass text message saying she was leaving town, both her phone and the pastor's were pinging off the same cell tower two blocks from his house. and when marie's mazda was dropped at the airport -- >> we've got james flanders' cellphone touching towers near the airport. why would his phone be near the airport? >> reporter: well, either james innocently drove marie to the airport, and neglected to reveal that, or he drove her car there to cover up a crime. no way to prove it either way. so they were stuck again. which is when jason, the youth pastor, remember him? out of the blue jason came to call. he had something the detectives needed to hear, he said.

i mean, that would take a certain amount of courage. >> absolutely. we would've never known about that if jason wouldn't have come forward. >> reporter: known what? the secret incident that got junior pastor jason involved. it happened soon after marie disappeared. when a very distraught james asked this church elder for help. >> he said, he goes, i need you to get me out of the country. i said what's going on? i said, does this have to do with maria -- marie? he said, "i can't tell you." never once said anything to me else, just it's bad. >> reporter: james seemed suicidal, said the elder. so he called a doctor friend. and the doctor committed the preacher to a psychiatric ward for ten days during which time jason anderson took over preacher duties. but then jason heard things. not about what happened to marie, but about polygamy. with other church leaders, he confronted james and tanya. >> reporter: this is a, forgive my saying, come to jesus moment?

>> it was the hardest thing i've ever had to do, myself, personally, was to confront my pastor. >> reporter: this -- your mentor, your senior guy. >> yeah, right. sure. >> reporter: and james admitted it. he had been sleeping with two women, in the same house. but then, youth pastor jason told the detectives, in that cloistered setting, james kept talking, and told a terrible story. >> him and marie had had a physical altercation before she went missing. and she had scratched him on his arms. >> reporter: james insisted marie was still alive the last time he saw her. >> i was just so in shock of everything. >> reporter: that was it. he could not continue as pastor. james would have to resign. he announced that he and tanya were leaving town. >> they were supposed to leave the following morning to say goodbye to some church members. and lo and behold, around 12:00 or 12:30 they'd gotten in that truck and they hauled butt. they went to arizona. >> they fled.

>> reporter: like thieves in the night with baby grace. it was a few days after they left when jason went to the police to tell his disturbing story. >> that they had a physical run-in the day that she went missing. >> reporter: then a piece of luck. before they left, marie's friend kay had asked the pastor and his wife for marie's belongings. they gave her marie's computer. the bad news was it had been erased but -- >> i brought it into the sheriff's department for them to take a look. >> we had our forensic tech reanalyze the computer and it gave us a beautiful copy of her phone download that she had done when she backed her phone up. >> reporter: wow. >> but maybe it wasn't so lucky. there were thousands of text messages, but they were an unreadable jumble of symbols and words. >> this particular coin though -- look at this, marie shot this video that did survive. showing the pastor hawking gold

and silver online, apparently while running the church. >> valuing this coin at over $500. let me tell you, that's exciting stuff. >> reporter: was james just a pastor? or part time flim-flam man? so this is where things stood when an anonymous tip came in. >> startling. if true, it would solve the case. >> and in the tip, it says that james buried her in the backyard. >> reporter: that's some tip. >> yeah. i can remember getting that tip and thinking, "no way." like, who would -- who would kill somebody and bury them in their own backyard? >> reporter: could be bogus, of course. just another false lead. but nesli was hopeful. >> we brought cadaver dogs and ground penetrating radar and -- we didn't find anything. >> reporter: nothing? >> nothing. >> reporter: no body. so what happened to marie? more months went by. police kept trying to speak with

james but got no response. then after a whole year, they tried again and he picked up. >> i had been asked by our attorney not to talk to anyone without him there. >> reporter: but he did talk -- talked for two hours, in fact, from his car. at times, sounding like he was the victim. >> what emotions have i felt over the past year and a month, you know? anger at marie for going and not letting us know what's going on, and then back to anger at myself for not making a phone call to get her help. and anger at myself for ever letting the relationship became what it became. >> reporter: the pastor said he knew he was the prime suspect. >> i am terrified of the prospect of marie taking her own life. and if she did, and i pray she didn't, i hope she did it very, very, very, very, very, very, very far away. because if they find her one little bone that somehow could be connected with her, there --

it's my fault. i'm sure it's the way people would look at it, it's james. >> do you know where marie is? >> no, i do not. if i did, i would go get her. >> did you kill marie carlson? >> no. >> reporter: and that was that. they were stalled. marie was missing and the case was getting very cold. >> reporter: coming up -- new revelations from the pastor. >> they were sending pornographic photos back and forth from the church. >> reporter: an answer at last to the biggest mystery of all, where was marie? >> i was pretty devastated. i felt like i missed her. the feeling of i could have found her six months after she was reported missing. seresto, seresto, seresto. jake... seresto, seresto, seresto.

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[ screaming ] oh, snowball. uh, is he ok? not in any way no. take that ok. you were just beaten by a rabbit. you don't even know it. [ ding ] oh, my pizza rolls. reporter: unlike a fine wine, a cold case doesn't get better with age, it just gets colder. and state attorney, bill eddins, wasn't optimistic it would ever be solved. >> what chance did you give it? >> i really felt that it was about a 50/50 chance of it bein' solved. >> reporter: eddins assigned one of his most experienced prosecutors, angela mason, to work on it. she wasn't optimistic, either. >> i was certainly vulnerable in

that i did not have a body. i was also vulnerable with the tanya element, that people thought she could be a suspect. >> reporter: and then three years after marie disappeared the most amazing thing happened. marie's computer yielded to a new forensics program, and out spilled in crimson blushing clarity text messages between marie and james. >> "i love you. i love you so much, and getting graphic details of what he wants to do with her." >> kinda pornographic. >> pornographic. even to the point that they were sending pornographic photos with each other from the church. >> reporter: some things are hard to un-see. we'll spare you. oh, and most important? everything stopped the day she disappeared. >> no credit cards, no phones, i thought that was strong evidence that she was in fact dead and not in fact missing. >> reporter: and her last conversation with a family member was -- >> she wanted out of the circumstances she was in. but she wasn't gonna leave her baby behind. >> reporter: and then there was this -- one of those sermons

posted on youtube just a month before marie vanished and now in the evidence file. >> now whenever someone is backstabbing me, lying about me, gossiping about me, trying to tear me down or whatever, you know what i want to do? my feelings say, 'choke the life out of them!' >> reporter: is that what the pastor did to marie? the detectives spelled out their case. circumstantial. difficult. but the prosecutors bought it. and james flanders was charged with second degree murder. persistence paid off. >> we were four and a half years in. most people would've given up by now. >> reporter: but, as the pastor waited in jail for his trial his attorney and former church member glen swiatek was optimistic. >> what did you think your chances were, if you went to trial? >> i didn't believe the state had second-degree murder. they didn't have a body. >> reporter: maybe not, but as the pastor and his attorney looked at the evidence that

might put him in prison for life just before the trial they made a deal. the state reduced the charge from second degree murder to manslaughter and james agreed to tell them what he did to marie. and where he put her. marie's family grudgingly agreed. >> that was the hardest thing. but i wanted to know where my sister was. i didn't wanna go years and years and years and not know. >> as much as i just absolutely hated to agree to it, i knew it was probably the only way. >> reporter: first, as part of his deal, the pastor told the story of marie. of the polygamy arrangement. >> it was as if she was another wife. okay? although we never had a ceremony or anything like that. >> reporter: he said marie even had a name for their relationship. >> marie called it a throuple. >> reporter: throuple. and then the pastor offered his

version of that last awful night. he claimed that marie was in a downward spiral mentally and erupted after he told her she should be hospitalized for depression. >> she hit me in the chest and i grabbed ahold of her and just hugged as tight as i could, and in the scuffle, we fell down on the floor. and -- when we hit the floor, we hit it hard. when i was realized somethin' wasn't right, i rolled her over and she wasn't breathin'. >> reporter: a fatal bear hug? not possible, thought nesli. and then she braced for the answer she'd waited five years to hear. >> did you bury marie in the backyard? >> i'll tell you exactly where it's at. >> is that where you buried her? >> yes. >> reporter: at that point, the detective got up and left the room. >> nesli passed me a note that said, "i missed her." >> i was pretty devastated.

i was in that backyard in 2012. >> not like you didn't look. >> yeah. but, you know, human nature. you still have -- the guilt. the feeling of -- i could have found her six months after she was reported missing. >> reporter: the pastor insisted that tanya wasn't around, was shopping, knew nothing. >> did you get her buried before -- uh, tanya came back? >> oh yeah. yeah. >> do you wonder whether tanya had more to do with this? >> i think that'll always be in the back of our minds. but you know, i think she may have known more than she wants to say. >> reporter: but tanya was never charged. and her defense attorney said she was truly shocked by james' confession. >> i could tell you, as a matter of fact, from having to tell her what happened she did not know. >> reporter: later that afternoon, nesli escorted james flanders into his former

backyard, where he marked with little flags the spot where he buried marie carlson, five years earlier. then he fell down on the ground, cried. told her, "i'm sorry." what an act, thought nesli. it took hours, but finally, almost five feet deep, wrapped in a blanket, they found what was left of marie. >> i was shaking. i was crying so much. i don't think i've ever cried so loud. >> reporter: nesli, and prosecutor angela mason wept too. >> it's my fault. >> reporter: back in court that afternoon, james flanders was sentenced to 15 years. with good behavior, he'll be out in 11. free to join tanya in arizona. and grace, whose mother he killed. >> he's gonna get to have a life after he's done. marie's gone forever. she doesn't get a life, especially with her kids, which

is, for most mothers, the world. >> reporter: jeff carlson had to tell his daughter, paris, her mom was not coming back. >> wasn't easy. what do you say? you don't know how to prepare them for the future of living with this, he deprived her of her mother. >> reporter: later, marie's family and many others gathered for a celebration of marie's life. they did her favorite thing. they sang karaoke. and nowadays, when marie's daughter, paris, comes to visit her cousin, esta's daughter, the two sit down at the piano and play. make music, just like their mothers, years ago. and grace? >> i wanna tell her all about her mom. it's one of those where i just -- i wanna show her, you know, like, "your mother really did love you."

>> reporter: maybe someday she'll know about that uncontainable woman who while she stayed brought joy. marie. >> reporter: that's all for this edition of "dateline." i'll natalie morales. thanks for watching. good morning, everyone. i'm alex witt at msnbc headquarters. breaking news. we have these new pictures of damage after a tornado strikes oklahoma. that's a state already reeling from severe flooding. >> we're going to learn in great detail that george papadopoulos had nothing to do with russia. >> the cart before the horse? some new questions about what the attorney general will find on his new mission. on the road and praising kim jong-un while blasting a u.s. judge. and they're cng