just down the road from home in the old military graveyard under the black prairie sod and the wind. >> that is all forhis edition of "dateline." i'm craimelvin. thank you for watching. i'm craig melvin a. >> and i'm natalie morales. >> and there is "dateline." this doesn't happen in our happy little world. >> their world shattered. a young mother strangled. >> we had a homicide. no suspects. >> also, no evidence. but police found a dark side behind that bright suburban facade. >> she slept with the children and the door locked. >> and finally, a vital clue. what happened to nancy? "the day she disappeared."

hello and welcome to "dateline extra." this story involves a young mother who disappeared one morning. her husband said she went for a run and never came home. a puzzling case that happened in a safe suburban neighborhood, the kind of place where crime is unexpected. but sometimes there are secrets hidden behind closed doors. here's keith morrison. >> reporter: nothing about that morning made any sense. >> it all seemed like just such a bad nightmare. this doesn't happen in our happy little world. >> reporter: it was a saturday morning in july 2008. the happy little world, a sweet and leafy suburb of raleigh, north carolina. a place a young family would aspire to. if you were someone like hannah pritchard, for example. >> there's always lots of friend-making going on through someone you meet. lots of cookouts and family functions.

>> reporter: like the one in the neighborhood the night before. so hannah would have heard party stories that saturday morning from her friend nancy cooper. would have. because nancy didn't show up. >> i hadn't heard from her maybe by like 10:00 i called her house. brad answered and he said oh, she went for a run. >> reporter: nancy was an athlete, training for a half marathon. brad cooper was nancy's husband. >> i was like, okay. when did she leave? i don't know. 6:30 or 7:00. i was like, she's not back? >> reporter: weird. if nancy had to cancel their meeting, surely she would have called. hannah cooled her heels. >> at 1:00, the phone rang and i saw on the caller i.d. it was her house. i answered the phone. hey, where have you been? he said, no, hannah, it's brad. nancy is still not back. >> reporter: now brad was worried. >> so i really started to panic.

>> reporter: especially when she learned nancy had also stood up another of their friends. so they called the local hospitals. no sign of nancy. they called nancy's twin sister krista up in canada. >> have you talked to nancy today? she went for a run and she hasn't returned yet, and we're very worried about her. can you call us back? >> you know about this kind of stuff. >> you'd think. >> reporter: krista calls her older brother jeff who is a police officer in edmonton, alberta. >> my first reaction is, okay, she's somewhere. you just need some space or some time. she'll turn up. >> reporter: but when nancy's parents gary and donna heard she was missing, they were gripped by something dark and cold. >> gary said to me, donna, this story is not going to have a happy ending. >> reporter: by afternoon, the cary police were involved. >> all i was told on the phone was it was a missing person's. >> reporter: when detective george daniels arrived, nancy's

neighborhood was already filling up with a small army of her panicked friends. nancy's family rushed to cary to join in the search. her brother brad made a public plea for help. >> if anyone knows anything, contact the police with any information they may have and again, thank you to everyone that continues to come out and >> sir, doou reporr: volunteers chased up and down the running trails where she loved train. they combed the surrounding parks and lakes and woods for this woman they'd grown to love since she and brad moved down from canada. >> when she walked into a room, that's where people wanted to be. >> reporter: she and brad were like a lot of people in cary. raising a family here, having got their start in another place and time. in brad and nancy's case, calgary, canada. that's where they met, back in '98. >> i really liked him. >> reporter: as did nancy's younger sister jill. >> this is someone who is warm.

you genuinely saw how much he cared for her. >> reporter: so brad became a helpful member of the family, even designed a computer systems in the family business. >> our i.t. guy was like, i want to meet the guy who did this, the networking system. he was kind of a legend in the i.t. world. >> reporter: he was so good, that cisco systems invited him to move to raleigh and work for the company. smart guy. >> smart guy. mensa or close i would say. >> reporter: but if nancy was to go with him to america, for immigration reasons, they had to be married. so in the fall of 2000, they said their vows, an intimate family affair. >> how did she feel about going to north carolina? >> a little apprehensive at first. lots of tears at the airport. fear of the unknown. but i think she was excited. >> reporter: and a few years later there were two bmws in the driveway, nancy had a vast circle of friends and brad a bright future at cisco where he'd become an expert in the marriage of internet technology and telephones.

one of just 152 such experts in the whole world. and best of all, two little girls, bella, born in 2004, katie, two years later. >> the best mother i've ever seen. she played and played and played. she was just so hands-on. >> reporter: and now they were putting up missing posters. sunday went by, all day monday, then monday evening someone called 911. >> as the chief of the cary police department, it is my very sad duty to tell you that the search for our nancy is over. >> reporter: it was a man walking his dog who found her. lying face down in water at the edge of a storm drain near a housing construction site several miles from the cooper home. >> our investigation is now a homicide. >> reporter: now they have to say good-bye. it was a measure of the woman that total strangers joined nancy's family and friends to share in the sorrow.

>> i continue to thank the community for their generosity and support. it's overwhelming. i am one of the luckiest people in the world. i'm a twin. sorry. i have a bond with nancy that no one in the world had. all i have to do to remember her is to look in the mirror. she will always be half of me. nancy, i love you, and i always will. >> reporter: now, of course, a homicide investigation was under way. but for detective george daniels, only this to go on, she'd been strangled, wearing only a sports bra and her diamond stud earrings. no marks on her body to indicate a beating. no struggle. no sign of sexual assault or robbery. it was a puzzle that landed in

his lap. >> she wasn't raped. she wasn't assaulted in any kind of way. the earrings weren't taken, then what was the reason for her to be over here? and what was the reason for them to do this if nothing was done to her? my shoulders carry a lot of names some i deserve others i don't but in the end only one name really matters because shoulders were made for greatness, not dandruff

use pantene shampoo together with 3 minute miracle daily conditioner. their pro-v formula is like a multi-vitamin. making your hair 2x stronger see the difference when you add 3 minute miracle daily conditioner. >> we had a homicide. no suspects. so we are dealing basically with

zero balance here. >> reporter: nancy cooper had been strangled. her barely clothed body found in a storm drain several miles from home. but why? there were no signs of rape or robbery or that any struggle had occurred. >> we start going back to where we started at saying, okay, let's look at everything again. >> reporter: there were reports from people who said they saw a woman who looked like nancy running that saturday morning. one man said he watched her for a good 30 seconds, then saw a van make a u-turn to follow her. and there were other reports of mysterious vans. friday night, one sped away from a cul-de-sac with no lights on. could any of this be tied to her killer? >> not walk away from anything at this point. everything becomes important. >> reporter: like conversations with her husband brad that weekend of the search. brad told detectives he and nancy were up at 4:00 a.m. saturday to calm their crying 2-year-old katie. then 6:00 or so, he made two trips to the grocery store after which nancy announced she was off to run.

>> we went to find the video records of him going in and out of the store which we found. >> reporter: but one of those talks with brad struck detective daniels as odd when he asked brad, did you contact nancy's family? >> he had told us no, but it could be because he's frantic about the situation and didn't have time to call them. >> reporter: then a little more talking and the detective learned there may have been another reason altogether. nancy and brad were having marital problems. >> he told me the last two months it seemed like they were getting better. when i asked him why they had problems, he told me he had an affair. >> reporter: so daniels tucked that tidbit away and went on for the search for nancy. after her body was found, things were different. the cooper house became a crime scene. police in and out turning the place upside down. and daniels kept his ears open because among nancy's friends and family, people were certainly talking. >> we're getting all this

information and having to separate what's important versus what's just part of a marriage. >> reporter: brad, remember, told detective daniels he and nancy were getting past the tension his affair had caused but that wasn't the story he was hearing from nancy's family and friends. >> she felt very trapped and didn't know what she was going to do. >> reporter: the marriage had been rocky from the start. brad seemed more married to his job than to nancy. then in the spring of 2007, nancy's close friend heather told her she had slept with brad though nancy confronted her husband. >> she just wanted the truth so they could fix it and go on. >> and he said it didn't happen? >> for a very long time. >> made her feel bad about thinking that it happened. >> reporter: until months later it was new year's eve day when brad finally came clean. yes, he told nancy. it happened. but he said only once and really it meant nothing. they went to counseling. and that's when nancy heard what she said was the real story.

>> brad says to the counselor, it's been going on for a long time. changes again from this one-night stand to, i love the woman. so nancy came away from that and said i'm finished. >> reporter: they agreed to split. sell the house. nancy would move back to canada with the girls. and then suddenly brad canceled nancy's credit cards, blocked her access to the bank accounts, put her on a cash allowance. >> i recall a time she was in the car with me and she called him and said i've got $2 and we don't have any diapers. >> reporter: nancy couldn't get a job. she had no green card. she began painting a friend's house to earn some extra money. when she did, brad reduced her allowance. she must have been furious at him. >> furious would be an understatement. >> she's very proud and she'd feel guilty. i'm not going to take your money. no, this isn't your job to support me and my kids. >> reporter: nancy began locking

important papers, including the girls' passports in her car. >> in february of '08, and it was awful. i had never seen nancy stressed out before. i had never seen her raise her voice in the house, and she was just miserable. >> reporter: miserable, stressed. each day uncertain. a painful struggle. an angry contest. >> she said this is just, i think, a game to show me how difficult it's going to be. it's his attempt to force me back into this relationship. >> reporter: then, as nancy was preparing to move back to canada and with brad's blessing take the girls, one of those moments on which lives can turn. the arrival from nancy's lawyer of a proposed separation agreement. alimony, child support, private schools for the girls, brad would have to travel to canada for his twice monthly visits. he made no counteroffer just told nancy the move was off. >> he saw what he was going to have to pay, and all bets are off.

>> reporter: and then brad got a hold of the girls' passports, found them in nancy's car. now they couldn't leave and nancy was trapped, too. but as the father, it's his perfect right to prevent those kids from leaving. >> yes. it's also a way to say, if i'm doing half the child care then i'm not going to have an alimony issue. >> reporter: to get her away from her troubles, nancy's family took her and the girls on vacation. >> how was it in the end when you had to say good-bye? >> heartbreaking. i had nancy in my arms in the airport in charlotte, and she was sobbing. and she said, mom, i just want to come home. and i'll never forget that day. >> reporter: it was the last time they saw her alive. and now that she was dead, nancy's family was sure brad had to be involved somehow. but detective daniels knew the demise of a marriage, bitter though it may have been, did not prove murder.

there was a lot more work to do. >> statistics say we should go back and key on the husband, things like that. and we're not going to walk away from that. at the same time, we're letting the investigation lead us wherever it goes. >> "dateline" returns after the break. what started as a passion... ...has grown into an enterprise. that's why i switched to the spark cash card from capital one. now, i'm earning unlimited 2% cash back on every purchase i make. everything. what's in your wallet? i'm ryan awith chantix.king everything i did circled around that cigarette. when i started taking the chantix that urge just slowly diminished and it was a great and empowering feeling. along with support, chantix (varenicline) is proven to help people quit smoking.

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>> reporter: in the days after nancy cooper's killing, the police chief here in cary, north carolina, tried to calm her jittery town. but her message was curious. seemed to imply that her officers knew something more than they were revealing. >> we still believe this is an isolated case. cary continues to be one of the safest places. >> reporter: isolated? how could she know really. >> and we still have not named a suspect or person of interest. >> reporter: oh, but nancy's family had. the very day krista learned her twin sister was missing, she called brad. >> and i asked him point blank at that point, what have you done? where is she? she didn't wait for an answer. she just hung up the phone. then the day after nancy's body was identified, her family went to court to try to get those two little girls away from brad. >> by 4:00 in the afternoon, we had papers in the judge's hand for temporary custody of nancy's children. >> reporter: the family acted so fast because, according to their complaint, brad's behavior was

so disturbing. before she disappeared, they'd seen emotional abuse. and they were sure she never went jogging july 12th. and then after she went missing? >> she was very standoffish and aloof with the family and he didn't contact anybody, and he just didn't want anybody around, didn't want any help. and it was strange enough to be alarming. >> reporter: so they feared for bella and katie's safety. >> did you think they were in danger? >> if he's in a place he could do this? could he bring harm to those kids? and the answer was absolutely. >> you have a million conversations. is this the right thing? we are sure this happened? at the end of the day you have to live with the fact that if we're wrong and this is way over the line, we did it for the right reasons. >> the judge determined the intense scrutiny brad was likely to face during a murder investigation put the children at risk. in late july 2008, the girls went back to canada to live with their slain mother's twin and her husband. >> kind of in a hurry. >> reporter: but brad, remember, had not been charged with any

crime. wasn't even a declared suspect and he fought hard to get his daughters back. which meant three months after nancy's murder, sitting for a videotaped deposition in which brad answered questions under oath about his marriage, his affair and what happened the morning nancy disappeared. so were police investigators listening? oh, yes, they were. >> was nancy a good wife? >> i would say so, yes. she was supportive. myself and of the children. very loving and generous. >> reporter: but there were two issues that troubled the cooper's marriage. one was money. the couple had serious debts. >> just this last week i looked at the american express card from january 2007. and of that, $27,000 was credited to nancy's credit card and mine was $17,000.

>> it was to rein in nancy's spending that he put her on a cash allowance. >> how much cash? >> at least $300. >> but nancy said brad was angry that they didn't have more money to spend. >> she referred to me as the budget nazi. i'm sure she's said that once or twice in a heated conversation. >> reporter: the other issue? brad's sexual relationship with nancy's best friend heather. the issue which finally brought their marriage to an end. he called it his indiscretion. >> i had sexual intercourse with heather once. >> reporter: it happened some time at the end of 2004, >> and where did this sexual intercourse take place? >> it took place in our home in the closet of the master bedroom. >> did you initially deny the relationship? >> yes, i initially denied it for approximately one year. >> why? >> i thought that if -- by denying it, it would go away and we could remain as a whole family.

>> reporter: but when it became time for the family to split, brad said he found the monthly terms of the proposed separation agreement unreasonable. >> child support, medical, private school, extra activities, you know, kind of added it up and i ballparked it at over $5,000 to $6,000. >> reporter: he also explained why he called off nancy's move back to canada. >> i realized that seeing the girls every other weekend would not be sufficient. >> reporter: and brad gave his account of the hours before nancy went missing. they were at a party across the street friday night. he left about 8:00 p.m. got the girls ready for bed. >> the kids fell asleep about 9:00 p.m. i probably fell asleep soon after. >> reporter: he was awakened previously about 12:30 when nancy came home. >> when she opened the front door and i heard her come up the stairs. >> reporter: again at 4:00 a.m. by katie's crying. took her downstairs followed by

nancy about 20 minutes later. >> nancy and i tag-teamed off and on trying to keep her calm. >> reporter: brad made two trips to the store. on the second trip, nancy called him, he said. he remembers being at an intersection when the call came in. >> do you know what time that would have been? >> i think looking at the cell phone records, 6:40 a.m. >> reporter: when he came back from the store the second time, katie had calmed down and nancy told brad she was going for a run. >> i took katie upstairs. went in front of my computer. read some e-mails with katie in my lap. >> reporter: and then around 7:00, he said, nancy left. >> how do you know that she left the home? >> i'm not sure if she says good-bye. either the door closed or she said later or something. >> reporter: that, he said, was the last time he saw her. three weeks after this deposition, three months after nancy's body was found, in late october 2008, brad cooper was arrested and charged with the murder of his wife.

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this is the hour's top stories. nbc news has confirmed a federal grand jury has approved the first charges in the investigation being led by robert mueller. the indictment is expected on monday. a federal judge ordered charges sealed and it remains unclear who will be charged . >> former president obama has been called to jury duty. the chief judge says obama will serve some time in november, but an exact date has not been set. back to "dateline." brad cooper was arrested goet of his wife. he admitted to having an affair, admitted that their marriage went through tough times. but was he capable of her

murder? once again, here is keith morrison. welcome back. >> reporter: he was just the right sort of guy when she found him. bright, quiet, stable. this computer genius so skilled, a multinational powerhouse had sought him out. >> we are ready to have the opening statements. >> reporter: it began in march of 2011, 2 1/2 years after nancy's death. >> nancy rantz cooper never went for a run from her house. >> reporter: the prosecutors howard cummings, amy fitzhugh and bob zellinger. they had their own idea of what happened to nancy beginning the night before she disappeared. >> we think she came home from this party and she had said some things in front of him that might have upset him a little bit and that he choked her. >> killed her then, their theory goes. put her body in the trunk of the car, drove her to the drainage ditch and returned home to manufacture an alibi. why? they started with that shredded marriage. brad's affair. cutting off her financially,

stopping her from moving back. she was increasingly desperate. >> jennifer, he's breaking me. i don't know how much i have left to fight. >> she told me when she slept at night, she slept with her jeans on and the keys in her pocket with the children and the door locked. >> he never beat her. it wasn't physical said the prosecutor, but he used financial power to exert absolute control. this was a form of domestic violence. >> she was in this abrasive, rough relationship at that point. he trapped her. he controlled everything about her life. >> wait a minute. nancy's allowance was $300 a week. would a jury think that was evidence of abuse? >> how do you tell a jury that he's depriving her? >> it's difficult but the facts still remain that there are these signs of control emanating from that cooper household. >> it doesn't matter whether it's $1,000 a week or $10 a week.

the fact of the matter is that it caused friction between the two of them. >> reporter: so the jury heard about that last week of nancy's life. the week of war with brad. with nancy's father on the stand, prosecutors played the phone message nancy left her parents after she returned home from that vacation with her family. >> the house was so dirty. there's an ant infestation on the table. i'm so furious. it was disgusting when i got there. >> reporter: the fighting escalated. on the friday, friend diana duncan said nancy was shaking with anger when she revealed brad withheld her allowance. because she earned her own money painting a friend's house. >> did she tell you what kind of day this was? >> this was an i hate brad day. she said that at least three times. i hate you, brad cooper. i hate you, i hate you. >> reporter: she lived across the street. it was her party that friday at which they fought openly.

>> her tone at that point was angry but also there was a tone of, you're an idiot. >> reporter: brad went home with the girls around 8:00. nancy stayed on. bitterly complaining about brad, even to strangers like donna lopez. and once in a while, said donna, nancy nervously looked across the street to her own house. >> how did you feel when you left that night? >> i was very worried for someone who i didn't know well. i thought i met someone really, really nice and told my husband something really bad was going to happen over there. it's really bad. >> reporter: so nancy disappeared. her friends' eyes all turned to brad. after all, they knew about the conflict and jessica adam knew nancy was supposed to be at her house at 8:00 a.m. that saturday to paint. when nancy didn't show up, she called the police. >> i was very concerned. i had seen brad in my house, and

he was agitated that week. related to the painting. >> reporter: it's a marriage gone bad. it's hardly proof of murder. nor was brad's conspicuous absence from her memorial service, nor his apparent lack of interest or cooperation as the police saw it in the murder investigation. these were suspicions. but there was no physical evidence linking brad to the crime. the prosecutor would say it was because he cleaned the house. he covered his tracks. well, but there it was. so what was the best evidence against brad? ironic perhaps, given the defendant's particular expertise. >> we knew we had this fabricated alibi to address. >> reporter: the issue was that phone call. the morning nancy disappeared. brad's cellphone registered a call from home at 6:40 a.m. when he went back to the store. proof surely that nancy was alive at 6:40.

unless, that is, unless brad placed the call himself. brad, the world class expert in internet phone technology. >> if anyone could do that it was the defendant. ultimately, he had the potential to make that phone call. >> reporter: in testimony that was frankly mind numbing -- >> that leverages something called either tapi or jtapi. >> reporter: an expert from cisco explained about ten different ways someone as accomplished as brad could have remotely made that call. >> the main ways are using a computer where you can program something into your computer and delay it so that a phone call can be made from your computer, from the computer's modem. >> reporter: but to do that, brad needed a certain router. conveniently, it disappeared from the cooper home. >> we knew he had this router. >> reporter: in fact said the prosecution, this cisco chat log proves brad ordered that router,

the 3825, took it home, months before the murder. >> you know the defendant had one of those 3825 routers? >> that's correct. >> and you never got that 3825 router back? >> no. >> cisco doesn't have it back. where did it go? it was never returned. >> reporter: but it was brad's own computer examined by the fbi which coughed up the most accusing evidence of all. evidence he'd already lied under oath. >> the kids fell asleep around 9:00 p.m. i fell asleep soon after. >> reporter: brad said he was asleep with his daughters when nancy came home from that party friday night. but brad's computer said otherwise. he was online until about midnight when nancy came home. >> he's been awake on his computer. when she comes in shortly after midnight, we think they argued and that a fight ensues and that's when he strangled her. >> reporter: and then the closest thing the prosecution had to a smoking gun, a google

map search. prosecutors allege brad typed in the numbers 27518. the zip code for cary. then zoomed into the exact location where nancy's body was found. when do they claim he did this? 1:15 in the afternoon on friday july 11th, 2008. the day before nancy went missing. proof of intent? maybe. maybe not. it wasn't much of a search. it lasted just 41 seconds. >> he didn't look anywhere else. generally you search a whole bunch of different places, and this is one place and it's only 41 seconds long. >> i don't think it would take very long if you look at the map and immediately recognize this desolate area, this beige area in a sea of green and then zoom into it, zoom into it, zoom into it and see where it is. >> reporter: of course, every prosecution has its flaws.

and this one, maybe, said the defense, they didn't have the right man at all. and maybe they didn't know nancy so well either. >> "dateline" returns after the break. on your medicare part d prescriptions, switch to walgreens. we make it easy to seize the day, so you can get more out of life and medicare part d. just walk right in for savings that will be the highlight of your day. walgreens has $0 copays on select plans and 100 points on prescriptions. so, swing by and save today. walgreens, at the corner of happy & healthy.

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the idea that they're in a bad marriage. that they're contemplating divorce. it gets you to a point you say, i need to take another look at this.

>> reporter: this is howard kurtz, defense attorney. this is what he thought about the murder charge against his client brad cooper. >> you need actual evidence to convict. and actual evidence is something they did not have. >> reporter: no physical evidence, said the defense attorneys, to tie brad to nancy's murder in those awful scenes from the cooper marriage the jury heard? no witness for either side had ever seen brad physically violent toward nancy. as for the $300 a week allowance, there was a reason the defense argued. remember, the couple had serious debt. and the defense offered contrasting scenes of the cooper marriage from another set of friends. >> people who had known the couple of years did not jump on this to bandwagon to paint this as an abusive relationship. >> reporter: remember that i hate brad day? the day the prosecution said the marriage hit its boiling point?

on that very day, said laura hiller, nancy was making a plan for saturday night, the day she disappeared. >> she wanted my husband and i to come over and play sequence with her and brad. >> was that a game you'd played with them before? >> yes, nancy introduced us to that game. >> reporter: when nancy's friend jessica testified they had plans to paint her house at 8:00 saturday morning, she had to have been mistaken said the defense because nancy knew brad had a tennis game at 9:00 a.m. with mike hiller. >> i specifically sought out nancy to make sure it was okay with her. >> did he indicate she had any other plans? >> there was talk she was going to jog. and she would be back by then. >> reporter: and there were people who claim they saw a woman they believe was nancy running. and it was proof, the defense said, that she was alive that morning. >> she was about 5'9", in good shape. >> reporter: this witness reported her sighting to the police after she saw nancy's missing poster.

>> how is it that the next day when you saw the flyer, you believed it was her? >> because she was so close to me and she had elongated face. that's what drew my attention. >> she wasn't the only one. this man said he got a 30-second look at her as he was driving to work. >> i saw a lady jogging on the right-hand side of the road. jogging towards the bridge. >> reporter: but did the police follow up? not for a long time, said these witnesses. >> they ignored everybody that believed they saw nancy for three months. >> reporter: same with those suspicious vans, said the defense. >> it was clear that the police had focused on brad to the exclusion of other people. >> reporter: it wasn't just brad who had been unfaithful, implied the defense. could someone else have wanted to silence nancy permanently? someone suggested the defense john mcpherson who didn't tell the police about an indiscretion with nancy. he said he held back to protect his family. it happened after a very tipsy

halloween party back in 2005. >> she began taking her clothes off. i took my clothes off, and we, i believe, started to have sex. i believe we stopped and got dressed and decided to never speak about it again. >> it seemed to observers as if you two were somehow blaming the victim. you we lking for other people she may have had relationships with. why was that important? >> theeason that people look to the spouse first is because affairs of the heart frequently lead to crimes of passion. so anyone with whom she had a relationship should be the subject of a police investigation. >> reporter: and there may have been other secrets, the defense charged. clues to nancy's life that they'll never know because -- and this was big -- a cary detective erased the contents of her blackberry.

accident, said the prosecutor. nonsense, said the defense. >> it's not something that happens accidentally. >> reporter: a prime example of its shocking allegation the police investigation was dishonest. why would the police have any motivation whatsoever to get rid of evidence in this case? >> not only did they start with an eye toward building a case against brad. they also started with an eye toward attempting to preserve nancy's reputation. and that phone would carry e-mails, text messages, pictures, videos. >> reporter: and you think it would have been exculpatory evidence for your client? >> i don't know what it was because we never did get to get in that phone.

>> reporter: and that call saturday morning from brad's house to his cell phone? the one the prosecution alleges brad made himself with that now missing router? they claim that he checked out a router and never returned it. >> the question is, did he generate a phone call not did he have the technological skill. they also took photographs of the house. they searched the house. and they have not once introduced any evidence that the router was in the house. >> reporter: hard drives don't lie. or do they? that was the question the defense raised when it came to those apparently damning results of the fbi's search of brad's computer. >> you are talking about a computer that we know was tampered with. >> you're alleging what? >> i'm not alleging. i'm stating as a fact, the computer was tampered with. there were significant anomalies that we found in the computer itself.

>> reporter: meaning, he says, that brad's computer was hacked. the 41-second google map search was planted. the prosecution had no smoking gun. so you're saying he didn't even search for that map? >> that's right. computer? >> yes. >> an fbi agent testified he saw no evidence of tampering, but the defense said it had experts who did. two of them. both of whom wrote reports. but trials have referees. and in this case, the judge ruled that neither one of those defense experts could testify about tampering. one, said the judge, wasn't sufficiently qualified. the other was brought in too late in the trial. but even if they had testified, there was one question they couldn't answer. if it was a hacker, who was it? >> i can tell you that police had access to it. i can tell you that anybody

within wireless range had access to it. >> what possible reason would the police have to put that map on his computer? >> i can't say that the police put it on the computer. i don't know who manipulated the computer. what i can say is, that a possible reason is if you believe somebody's guilty, and that you don't have any evidence against them, well it's perfect evidence, isn't it? >> could those 41 seconds put brad cooper in prison? for the rest of his life. >> "dateline" returns after the break. wrong size pad and can experience leaks discover always my fit. find the number that's right for your flow and panty size on the top of any always pack. the better the fit, the better it protects. always.

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for two long months attorneys for both sides hammered at the question, what happened to nancy cooper? the defense charged the police more than dropped the ball, their investigation was dishonest. the erasing of nancy's blackberry, for one thing, had to be intentional, said the defense. nonsense, said the prosecution. besides, they said they already found what they needed from that phone through other sources. >> we had her phone records so we knew everything she had done. we had the billing so we could tell how much texting she did or didn't do. we already knew all her friends. >> and the idea that police might have inserted the google map search on brad's computer, well, they couldn't have, said detective daniels. >> none of the people that work for me or worked in the department would have had the knowledge to go in and do something like that. >> the defense charged that

police ignored those possible sightings of nancy and those mysterious vans for months. >> the defense was thinking that the jury wasn't listening. the police indicated that they followed up with every one of those people. >> as for john pearson, whose indiscretion with nancy should have made him a suspect, at least according to the defense, he had an alibi. on that friday night pearson spent the night with heather. the very same woman behind brad and nancy's breakup. >> at the beginning of the tapes -- >> still, as the long trial finally wound down, the defense hammered home its claim that the police and prosecution bought in to a whispering campaign by nancy's friends against brad. >> it made it easier for them to simply let the gossip about brad become their reality even when the facts and the evidence did not fit it. and now, the police department and the prosecutors are willing to send an innocent man to rot

in a dungeon in essence for the rest of his life. >> but there were facts, said the prosecution, to send broad cooper away for life. >> fact the defendant googled where he was going to place his wife peace body. fact the router that could help him automate a phone call is also now missing. fact, nancy cooper never left that house the morning of july 12th. >> so the jurors adjourned to deliberate. guilty of first degree murder, second degree, or not guilty. and nancy's family, having listened to weeks of confusing circumstantial evidence, worried. >> if i was hearing this for the first time would i feel comfortable sending someone to prison for the rest of their life? >> the jury stayed out for two days. and then -- >> has the jury reached a unanimous verdict? >> yes, sir. the verdict of the jury reads, we the jury, by unanimous

verdict, find the defendant, bradley graham cooper, to be guilty of first degree murder. >> i cried for hours. >> yeah, i cried for hours. relief, yes, it's over. there's a conclusion. and it's justice for nancy. and now we can all go home. >> and brad? >> obviously brad was upset. he knows and feels that this is not over. >> in 2013, an appeals court overturned bradley cooper's conviction. deciding the judge should have allowed more defense testimony regarding the laptop evidence. a new trial was ordered. but while awaiting his second trial, cooper pleaded guilty to second degree murder, and was sentenced to approximately 12 to 15 years. and nancy there's a black granite bench in cary park, the police she once ran, her adopted

town's way of remembering. the cooper girls bella and katie are growing up in canada with nancy's twin sister krista and her husband jim. their cousins were with them the day we came to call, and so, seven little girls scampered happily about, their pleasure infectious. and for the adults, bittersweet. >> here we go. >> sad that nancy's not here seeing it. >> absolutely. that's the tough part for me. >> what do they understand about mother and father? >> what we've told them is that mommy nancy was killed by a bad man. and but she's in heaven, and that man went to prison. >> tell them the tragic story of a man and a woman who sank in the undertow of what once was love. >> we got an outcome that nancy deserved. but it's also not a winning hand

for anybody. and brad lost his life, as well. there's many things that were lost. lives that have been forever changed. >> that's all for this edition of "dateline." i'm craig melvin. thank you for watching. good morning i'm milissa rehberger. it is 7:00 in the east, 4:00 out west. we're about to find out who will be the first person or persons charged in robert mueller's special probe. hear from an attorney about whether it could be a big fish or a little fish. how will the president react if the person is a close member of his team? a new insight this morning from a white house lawyer. new criticism of the republican tax plan. one of my guests will explain why he's calling it trickle-down fairy dust. but we begin with new reaction from the white house on the eve of a bombshell in