i loved everything about nikki. she was a phenomenal, amazing person. she loved those girls. pretty much her pride and joy. it's hard for me to even -- it's hard. tea it's real hard. >> pretty, poised, perfect. her twins were her world. >> they were so precious. >> the three of them were a very tight unit. they were all she had. she was all they had. >> then came that awful day. >> these two beautiful 16-year-old girls had come home from school and found their mother murdered. >> they were rocking back and

>> what had the girls seen that day? could they provide a clue to help crack this case? >> we were told by the twins that nikki had a second boyfriend. >> two boyfriends? >> two boyfriends. >> jealousy, passion. revenge? >> she was fearful. >> she contacted the police. >> what secrets might the twins reveal? >> it's terrifying. is it possible that this could happen? >> i was shaking. oh, my god. oh, my god. you couldn't even imagine. >> i'm lester holt, and this is "dateline." tonight, watch for the double twist. here's keith morrison with "bad blood." once in a while in a complicated life, a woman can get lucky, which is why you're looking at the sweet little town called conyers, georgia. antique downtown, ringed by gated communities, good schools, a sheen of newness. it was really pure luck that

brought nikki whitehead to this house, in this quiet, safe neighborhood. just far enough away from atlanta, that capital of overheated ambition down the highway. here in conyers, she could give her beautiful twin daughters a better life than hers. but of course luck, fortune, fate can go either way. sometimes in ways very hard to comprehend. >> everything about this goes against nature. >> how could somebody do that? >> it was definitely the bloodiest crime scene i've ever been to. >> in the next few minutes, you will know exactly when it happened, where it happened, how it happened. but, of course, the real question is why it happened. and the answer to that, as you will see, it's kind of complicated. but that's how nikki whitehead's life was. >> i loved everything about nikki. >> yucca harris grew up with nikki, could see she was a wild chilre

irresistible. >> nikki was, to me, a phenomenal, amazing person. >> yes. and she was effervescent, said nikki's mother, lynda. bigger than life. >> she was the kind of person that when she comes in a room, she just takes over the space, you know, with her personality, her laughter. >> but when nikki was 12, oh, boy, a handful. lynda was a single mom with other kids at the time, so she agreed to let young nikki move in with della, nikki's grandmother. but della let the girl run wild. boys, parties. >> grew up kind of fast. and then later, she became pregnant at the age of 18 or 19. so we moved kind of fast. >> yeah. >> yeah. >> pregnant with identical twins whom she named jasmiya and tasmiya. jas and tas. bo

briefly, then gone. and their mother figure? nikki's grandmother, della. nikki's mother, lynda, didn't like it. >> i wanted nikki to get her own place, establish her own life, and my mom would discourage that. she would find ways to tell her, no, you're better off here. >> that's how it went for years. but nikki had learned how to style hair and was doing well at it. and eventually saw the possibility of independence. so she eventually wanted to kind of get out from della's control, right? >> definitely, she did. she wanted to -- as the girls got older, she definitely wanted to take control of her life. >> and then one day in 2000, nikki was shopping at the mall. and robert head just happened to be in exactly the right spot. >> i was at the fountain one

afternoon about 6:00. and there walks nikki coming into the mall. >> your eye caught her? >> yes, i couldn't let her go get away. >> that he was old enough to be her father didn't matter. robert was in love. he persuaded her to go to dinner that very night. he took her dancing. he bought her nice things, treated her like a lady. >> she was my movie star. that's what i called her, my movie star. >> his movie star with two sweet daughters he also soon loved as if they were his own. and that's how nikki came here to safe, secure conyers. this is robert's house. here, they made a family. unusual in some ways, as you will hear. but -- >> it was nice. it was really nice. everything clicked just right. >> and she wanted her life to get even better. so while she kept her job as a hairstylist, she enrolled in atlanta's bauder college to study fashion design. >> that's when i actually learned that nikki was a hai

>> rhonda anderson taught a couple of nikki's classes. she thought nikki had a sense of purpose, whether it was about her kids, her fashion, or other people's hair. >> i came in to class early one day, as i normally do. she looked up at me and said, miss anderson whaer, what's goi with your hair? i said what? excuse me? nikki asked me this question, "do you have a hairstylist? does she know you have your hair looking like that today?" i said, "yes and no." she said, "miss anderson, i'm giving her one more chance. one more chance. if it's not right, i'm taking over." >> rhonda loved nikki, and nikki loved her girls. she put the twins in dance and music classes. at school they won awards. >> their teachers described them as almost angelic, sweet, and happy and engaged. and there's pictures of them, you know, one on each of nikki's arms. >> catie beck is a reporter at af

>> teachers describe them that way, that they have a sweet demeanor in their classrooms and with their classmates. they were almost timid. >> and then as they reached their teens, they changed somehow. in the ways children often do, in the way nikki herself once did. and just like nikki, the twins were sent to live for a couple of years with the rather permissive family matriarch, della. until 2010 when nikki welcomed tas and jas back, all together again in robert's house. a fresh start. and nikki turned up at school beaming. >> she was in a very good mood. she looked great. she had a new look with her hair. and she had braids in. and she was happy. >> as if the braids in her hair were kind of an announcement. her girls were back. >> they were pretty much her pride and joy. >> oh, you stahi

her? >> yeah. it's hard. it's really hard. >> it was january 13th, 2010. a sheriff's deputy happened to be in the neighborhood. the girls had just come home from school. the deputy saw a look of horror on their faces, heard their screams as they came pounding on his car. >> one of the twins ran up and literally beat on the side of this car and told him that they had come home from school and found their mother murdered. >> when we come back, exactly what had happened? >> they were going in and out of fits of tears and crying. traumatized, disturbed. >> two distraught daughters are about to reveal a clue. >> we were told by the twins that nikki had a second boyfriend. >> two boyfriends? >> two boyfriends. > two boyfrie.

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wednesday afternoon, january 13th, 2010. a gated community in the town of conyers, just east of atlanta. 16-year-old twins jasmiya and tasmiya arrived home from school, walked in the front door, followed a bloody trail, and there she was in the bathtub. their mother, 34-year-old nikki whitehead. very, very dead. >> as you walked in -- >> the mess that greeted arriving conyers police detective chris moon told a terrible story. >> this was a long, drawn-out

fight. nikki was fighting for her life for several minutes. this was not a quick attack and over with. she fought here. she was struck in the back of the head. she had a laceration to the back of her head. there was blood on the door, on the door handle as if -- >> as if somebody tried to get out of -- >> to get out, yeah. then along this wall, you could see a bloody imprint of hair braids, which nikki had her hair in braids, where she fell, slid down the wall. the most severe blows came when she was facedown in this area. this is clearly where the assailant got on top of her from behind and started stabbing the base of her neck. >> a huge amount of blood here? >> yes. this was the largest pool of blood, in this area here. >> she was dead, or near dead, when her assailant dragged her to the bathroom. and that's where she was in a tub of water, what her daughters saw, before they ran to the street screaming. >> as we get there, you have

these two beautiful young 16-year-old girls that discovered their mother murdered. >> conyers police captain jackie dunn wanted to get jas and tas away from the house. that's when he noticed they were hurting themselves. >> one of them was biting their arm. and we were like, "hey, why are you biting your arm?" she said, "i'm so upset. i do that when i'm upset." >> this was the worst kind of case. detectives need information fast. how do you get it from children who have just left their dead mother? [ crying ] >> they were going in and out of fits of tears and crying. >> i want grandma. >> asking for their mom. >> i want my mama. >> they both seemed to be rocking back and forth, you know, contemplative, traumatized, disturbed. >> i want grandma. >> it will be okay. it will be okay. >> i can remember thinking, man,

i hope there is a suitable family member to adopt these girls because they -- they really need -- >> sure. >> -- somebody to reach out and be good parents for them. >> word spread through the late afternoon gloom. a friend called yucca harris. >> she had asked me when was the last time i talked to nikki. i said, well, i talked to nikki saturday. she had told me that you may want to go over to her house because she said the helicopters were there. and the news reporters. >> tell me when you heard that, what did you think? >> i don't know. it was like tunnel vision. i was just in slow motion. >> yucca called nikki's mother, lynda, told her something bad was going on over at nikki's. >> i was so nervous, i didn't know what to do. i was like -- oh, my god. oh, my god. i was just shaking. i could hardly drive. >> lynda pulled in to her daughter's neighborhood and saw a police officer. >> said, "ma'am, can you pull over there?" i said, "no.

house." he said, "ma'am, will you just pull over there, please?" i pulled to the side. i said, "what is going on?" he said, "ma'am, the only thing i can tell you is your daughter has expired." >> there is no getting over news like that. as nikki's family tried to take it in, investigators set to work figuring out who did this. the girls said their mother was still in her room with the door locked when they left the house for school at 7:30. >> we missed the bus. so we had to walk. >> perhaps the crime scene would yield more clues than the girls could. lieutenant chris moon headed back there.

phones, computers, indications -- you know, typically victims are going to have called or spoke weekend their assailant just before the murder or around the time of the murder. >> the attack did not look random. it was not rape, but it was so violent. >> that suggested rage. and when you look at -- at a rage murder, it's usually somebody very, very close to the deceased. >> so naturally the first person they wanted to talk to was the man of the house, robert head, nikki's boyfriend. but robert wasn't around. >> when was the last time you saw robert? >> yesterday. he left -- he came in on sunday. he stayed for a day. he left. >> here's the thing. robert was a long haul truck driver which explained his absence, but not where he was, especially when nikki was murdered. >> we had to find robert, and we had to check on his gps. >> that takes a while, right? >> yes, sir. >> meanwhile, detectives spread out through the neighborhood, knocking on doors.

unusual? a couple of neighbors said they saw a red car in nikki's driveway that afternoon, a car they had never seen before. and a black car on the street, too. they asked the girls who could have been there. >> does your mom have any other friends or anybody else that would come over that you know of? >> she talks to a lot of men. >> she talks to some men. but the only one i've been hearing her talk to lately is joe. >> joe? who was joe? >> we were also told by the twins that nikki had a second boyfriend, joe carter. >> two boyfriends? >> two boyfriends. >> now that got the investigators' attention. time to dig a little deeper into the life of nikki whitehead. coming up, two boyfriends, two possible suspects? >> bad blood involved? >> they were clearly having an argument, yelling and screaming over the phone. he was an immediate person of interest. >> when "dateline" continues. at. with non-insulin victoza®.

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detective in conyers,

course in the short life of nikki whitehead, found stabbed to death in the home she shared with her live-in boyfriend, robert, and her twin teenage daughters, jas and tas, who at least had each other for support. >> what are we going to do? >> the girls put their arms around each other. and "it's going to be okay. we're going to find out who did this." they were clearly relying on each other to get through this. >> but they were able to convey some real information. >> any idea who she was talking to? >> it was joe. >> it was joe? >> their mother had a second boyfriend. a man named joe carter, a local barber whose shop was right next to nikki's salon. love triangle? sounded to veteran homicide detectives like a potential recipe for murder. first they talked to robert, boyfriend number one, who was on the road in his long haul truck. how did he react to the news?

>> it was easy enough to check on robert. gps records put him a full day's drive away when nikki was murdered. and when they met him, as we did, they could plainly see his grief was real. >> because that was my better half. she was gone, you know. it's a hard thing. >> this was how detectives discovered the unusual nature of robert and nikki's relationship. robert told them he knew about the other boyfriend, wasn't secret. he didn't mind. he said he wanted nikki to be happy when he was away on the road. >> he's a truck driver. when he was home, he expected for her and him to be a couple. and when he was away, he realized that she was going to have other relationships. >> but what about joe? how did he feel about that? he was upset about something, said the twins.

they said joe and nikki had a nasty, loud argument on the phone. >> all she told joe was that he couldn't come over there last night. >> was there some suggestion that there might have been, you know, jealousy or bad blood involved? >> well, that's what we immediately thought. and so obviously he was an immediate person of interest. >> so he was. and, remember, a neighbor spotted a black car near nikki's house the day she was killed. joe's car perhaps? >> do you know what joe drives? >> no. i know it's a black car in the driveway, and it's a black car. >> rockdale county district attorney richard reed. >> we need to look at joe carter. especially since nikki and joe had been in an argument. they were breaking up. >> that's a dangerous time in a relationship. >> it can be. it can be a dangerous time in a relationship. >> it wasn't hard to track joe down. he was in the barber shop where he worked. >> it was around closing time.

out of there, and they approached me and my friends. then they basically said that she's passed away. i mean, she's dead. i was shocked. i was just in shock. >> how did he react? >> he immediately started weeping. >> he didn't know about -- claimed not to know? >> he claimed not to know. >> but reactions don't always tell the real story. >> they was basically asking about me and her relationship, when was the last time i seen her. and i started to realize i was a suspect. >> detective moon did what any good detective would do. he looked for the sort of marks nikki might have left on her assailant's body. >> looked at his hands, looked at his arms. he took off his shirt. >> but joe was clean. not a suspicious scratch on him. and detectives learned that black car outside nikki's house didn't belong to him. still, they brought him in for questioning, hooked him up to a polygraph and asked pointblank if he killed nikki. >> and the polygrapher

determined that he was not deceptive in answering questions. >> i wanted them to find the killer, and i wanted them to know that it wasn't me. >> so that's it for joe? >> it appeared that joe was not involved in the death of nikki whitehead. >> so two boyfriends, and two dead ends. in addition to robert head and joe carter, it could have been a stranger, could have been another -- did you look into that possibility? >> we did. >> yes, and they still wanted to know who owned another car, a red one, that was also seen in nikki's driveway the day of the killing. it didn't take long to find out. it belonged not to a murderer at all but a friend. >> nikki had missed a hair appointment with this friend. and the friend had come by, knocked on the door, and had not been able to make contact with nikki and left. >> imagine had she opened that door. such a grisly scene, so full of

so who killed nikki? someone close? then as they struggled to figure it out, investigators encountered in their own police file something rather stunning. coming up -- >> i just woke up, and my daughter is gone. >> your daughter was abducted? >> i don't know, ma'am. she's gone. >> family secrets. there were a few yet to be revealed. >> it turned into a fight. >> a physical fight? >> a physical fight. and she contacted the police. co. everhas a number.olicy but not every insurance company understands the life behind it. for those who've served and the families that have supported them, we offer our best service in return. usaa. we know what it means to serve. get an insurance quote and see why 92% of our members plan to stay for life.

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the investigation into the murder of nikki whitehead was not offering up any usual suspects. the two men in her life, robert head and joe carter, had been eliminated. and a home invasion seemed very unlikely in her gated community. >> there was no history of any peeping tomas. no histori

so we just kept coming up with dead ends. >> they felt sure this had to be a rage murder, so violent, so protracted, which made it very likely it was something nikki knew. even possibly a family member. >> we started getting in to some of the family dynamics. >> that's when they turned up, in police files, this remarkable incident back in 2007. one brief snippet of family history, but an event that changed everything that came after . >> conyers, 911. >> yes, ma'am. i woke up, and my daughter is gone at the house. >> that was the voice of nikki whitehead. >> meaning your daughter was abducted? >> i don't know, ma'am. i woke up, the door was unlocked and she's gone. i have twin girls and one of them is gone. >> how old is your daughter? >> oh, lord, 13. >> you can hear her terror. >> oh, lord. my worst nightmare. >> do you think maybe somebody came and got her? >> i don't know if somebody

i don't know. >> but a few hours later, nikki learned that her daughters did do stuff like that. jas had not been kidnapped. she'd snuck out to fool around with a boy. >> up until that day, i believe in nikki's mind she had perfect girls. nikki realized that they weren't necessarily the girls that she thought they were. >> nikki was determined to help her girls avoid the mistakes she made at their age. so she cracked down on curfew, on boys, on cell phone use. the following months would be familiar to many parents of teenagers. screaming, slammed doors, stoney silences. and then one summer night in 2008, a year after jas sneaked out of the house -- >> a big argument, and it turned in to a fight. >> a physical fight? >> a physical fight in which tas and jas against their mother. at that time, i think she felt fearful, and she contacted the

police. >> was it the right decision, to call the police? that ensured the family ended up in juvenile court. nikki asking the judge to help her teach her daughters a lesson. instead, seemed to lynda the judge was blaming nikki. >> i guess the judge thought they were too cute and too smart that -- nah, they couldn't be doing, you know -- he did not take it serious. >> what did he decide to do? >> well, he asked my daughter, he said, do you want your kids to come back home? and she said, no, your honor, not unless they understand that i'm not going to tolerate that kind of behavior. and so he was like, you mean to tell me you don't want your kids to come home? >> what nikki wanted was a court-sanctioned demand that her daughters obey the rules, but that is not what she got. instead, the juvenile court

judge sent the girls to live with della, their great-grandmother. what were they doing while they were at della's house? >> pretty much whatever they want. they kind of ran wild. >> and got in trouble repeatedly, in school and out. >> shoplifted, smoking marijuana, seeing the wrong type of boys. >> well, she didn't want that. she knew -- you know, she was going back to when she was their age in her grandmother's custody. she didn't want that for her kids. >> it seemed to nikki that della was undermining her, had somehow stolen away the daughters who mattered more than anything else in her life. >> she wanted them back. really wanted them back. >> how did you know this, how did she express this? >> she said it every day, "i want my girls. i'm going to fight for my girls." >> and in january, 2010, nikki finally won. the judge ordered the girls back to nikki's, and jas and tas did not like it, not one bit. >> they started screaming and hollering, "we don't want to go ck

>> in court they were doing this? >> yeah. >> nikki told her mother not to worry. >> she said, "i'll be fine. they'll mellow out. you know, they'll come around." >> a few days after the court's decision, on a saturday night, nikki put on a welcome home party for the girls. >> they hugged me, you know. they kissed me. >> and that was the last time yucca saw nikki. four nights later, there they were, jas and tas answering the increasingly pointed questions of a couple of detectives. >> can you tell me what happened when you got home today? >> seemed a little odd that the girls were still wearing outdoor gloves. the detective asked, could you take them off, please. >> let me see your hands and your arms. what happened here? >> when we did that, we did see a cut on one of them's hands. we saw bruising on the knuckles and the skin marks and bite marks. >> bite marks? >> and we asked them to explain

>> the bite marks could have been self-inflicted. remember, the girls were so upset on the way to the station they were biting themselves. and the other cuts and scratches? the twins told the cops they had been fighting with each other. >> fighting? >> we didn't get along yesterday. >> i just have rules -- >> as they told their story, detective dunn took a good look at jas and tas. and a disturbing idea settled down somewhere in his brain. >> i haven't made up my mind, but i'm suspicious. coming up -- suspicious? were there reasons to be suspicious? >> we watched the high school video surveillance, and you see the twins showing up about 2 1/2 hours after they should have for school. >> what were the girls doing the morning of the murder? the morning of the murder? so i asked about adding once-daily namenda xr to her current treatment

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there's a look, a way of talking that suggests a thing that spoken words most certainly do not say. as nikki whitehead's petite teenage daughters told their story, how they discovered their mother's body, how horrified they were, the detectives watched their eyes. their tearless sobs. saw their bruises and cuts. and just knew. >> they're not behaving consistent with somebody that found their mother murdered. >> mind you there's a hurdle a person has to overcome to imagine that these two sweet teenagers might have been involved somehow in what could only be ca

though nikki's mother, lynda, remembered clearly how angry the twins were just a week earlier when the court sent them back to nikki. >> when jas came out, she looked over at my daughter and said, "if i got to go back home with you, i'm going to kill you." >> you heard that? >> i heard this, and it stunned me. >> but teenagers sometimes do talk that way. doesn't mean they actually do anything about it. so the detective set about fact checking the twins' version of the events on the day of their mother's death, starting with their claim that they had to walk to school that morning. >> they told us that they had overslept a little bit, that they had missed the bus and had walked to school. >> it was a rush, said the girls, but they did get to school on time. >> made all your classes today? >> yes. >> so the cops did what the cops do. they checked surveillance tape from businesses along the route to school. and what do you know? >> law enforcent

the girls walking down the roadway next to the gas station a little after 10:00 am that morning. >> nowhere near on time, as the school surveillance camera confirmed. >> we watched the high school video surveillance, and you see the twins showing up about 2 1/2 hours after they should have for school. >> so the twins were caught in a lie, and it was a big one. but it wasn't proof of murder. they flatly denied any involvement in that. even when they were put in separate rooms, they presented a united twin front. >> they wouldn't sway. there was never any disloyalty to each other. they never said a negative comment about each other. >> getting one to flip on the other was not going happen? >> no. >> after those interviews, they released the girls. the juvenile court farmed them out to family and friends. and the police sent their dna and photos of their injuries, like those apparently self-inflicted bite marks, off

and then they waited, pretty sure science would tell them that these sweet little girls were anything but. did they appear manipulative to you? >> absolutely. i'll give you a for instance. jasmiya is in one room, tasmiya is taken to a smaller interview room. it's apparent that tasmiya knows there's a camera and recording system in the room, and she starts to pray. >> i really want them to catch this person. please, god. >> she knew at some point in time somebody would watch that video, and they would see the young, innocent, sweet girl, asking god to help law enforcement find the person who did this. >> meanwhile, at the glacial pace these things occur, the crime lab worked on the dna and poured over those photos of the bite marks. one on tas' arm was the impression of a big, ugly bite. they compared the contours of that bite to a mold of nikki's mouth.

the similarity was uncanny. >> nikki was the most likely source. >> had their mother bitten them trying to fight off an attack? >> the bite mark on tas' arm would be consistenta if she had her mother in a choke hold from behind and her mother, nikki is biting her or trying to get away. >> and when detectives saw the twins biting themselves right after the murder, maybe that was an attempt to cover up evidence. then the dna results came back. they knew they'd find nikki's blood, but remember, one of the twins had fresh cuts on her hands. and, sure enough, in a smear of nikki's blood mixed with her likely assailant's, a match. it belonged to one of the twins, but which one? >> they're identical twins. they have identical dna. we don't know, couldn't tell for sure which twin the blood came from. >> by this time, the twins had been out in the world without a word from the police for five months. wxia reporter catie beck. >> i think those month built

their confidence. built almost an arrogance that we're going to get away with this. >> so you can only imagine how it was may 21st, 2010, just after school. how did they react to being arrested? >> shocked. they -- they thought it was over with. it had been five months since they had heard from us. >> the arrest was big news in atlanta. two sweet, little girls charged with the murder of their mother. who would have thought? >> i mean, people were riveted by the story. >> oh, yes, they were. and when the twins finally told their version of events that cold morning in january, the city was riveted all over again. coming up -- >> we're all going to die today. >> the fatal struggle. did their mom start it all? >> charged forward. i kept telling her to stop. just stop. just stop.

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it's a complicated thing, lots to do if you're a prosecutor preparing a murder case against pretty twin teenagers. so d.a. richard reed was interested when one day defense attorneys suggested they wanted

>> my response is it's great to hear it from you. but i want to hear it from them. and so i'd like to talk to your clients. i'd like to ask them questions. >> and that's how d.a. reed met the 19-year-old jas and tas, and heard them confess they did kill their mother. but was it a confession really? in fact, said the twins, it wasn't their fault. she started it. >> she started cursing and stuff. i think she was mad about us being late. >> that morning they said nikki was furious that they were late for school and picked up a pot in the kitchen, they said, and swung it at them. >> she called us whores and sluts and everything like that and stupid and everything like that. and she -- she threatened us. we all gonna die together. >> that's jas. then tas picked up the story. >> you took the pot away from your mom.

what happened then? >> she, like, kind of started to charge forward. not at me, though, at jas. >> now nikki had a knife, said the girls. they tumbled room to room trying to get it away there her before she cut one of them. and in fact, said tas, that's how her finger got cut. >> i kept telling her to stop. just stop, just stop, just stop. >> but she didn't, they said. >> trying to punch her, i guess. i think tas stabbed her. she stabbed her and -- >> at this point in time, how

>> just once. >> at this point exhausted. they all called a truce. it didn't last long. >> they said mom lunges for the knife. then it's on again. then she drifted off in the water and died. what did the d.a. think about the girls' tale of self-defense against a mother gone berzerk? did you believe them? did you believe everything they said? >> no. still don't. >> the idea that nikki launched an attack on her own daughters? difficult to believe, said the d.a. sheer nonsense is what nikki's mom called it. >> my daughter never hit her kids. they never had a spanking, more or less. anybody that knows nikki knows that wasn't her behavior. >> it was very clear, said detectives that worked the case, that nikki was the victim of an unprovok a

she had 45 stab wounds. her spinal cord was almost severed. >> nikki fought for her life. we think she fought defensively. you can see where she's on her back some of the time fighting off people that are attacking her from above with knives. >> as for the girls' claim that they put their dying mother in the tub to keep her warm, as they watched her fade away, fiction through and through said the police. >> we think she was dead before she was placed in the tub or she would have bled into the water, and the water would have been bloody. they were putting her in the water trying to wash off the crime scene. wash off the evidence. >> in truth, said the detectives, these girls were remorseless, defiant, brilliant little actresses. remember how they sounded just after their mother's death? >> mommy. >> i hope you catch the person that did this, please, god. >> listen to the little darlings when they didn't know they were playing to the cameras. this was recorded in thek

arrest. sweet little girls? hardly. [ bleep ] they got [ bleep ] evidence. they can't do nothing with [ bleep ] evidence. man, get real. did you find a murder with my fingerprints on it or something? man it would be different if they said we have a murder weapon. please do that. please find a murder weapon. thank you. >> they are aggressive. they are angry. they are combative. >> and one more thing -- tucked away in one of the girl's bedrooms, police found this journal. inside, in childish handwriting, a death sentence. they were notes to each other, said the d.a., written just before the killing.

"she don't care. she selfish. we got to get rid of her." to which the other twin responds, "that's what i think also. she gotta go asap." >> it may be the most telling piece of evidence that the whole death of mom may have been premeditated. >> still, the d.a. worried a good defense attorney could spin the family's turbulent history, the juvenile court drama, n nikki's two boyfriends and somehow sell the jury on self-defense. >> it would have been an ugly trial. and i think to some extent would have been a misrepresentation of nikki's life. >> though he didn't like it much, he let them plead guilty to the lesser charge, voluntary manslaughter. 30 years for each. not enough, said nikki's mother, lynda. >> these children have killed my child brutally. and you're going to give them 30 years? they shouldn't even be able to walk the street. i know these are my grandkids, but come on now. i mean, if they can do this to their mom, god help us all. >> the questions you go over and over in your head are like what? >> how everything about this goes against nature. how thrs

you and raises you and loves you and gives birth to you, how you could watch that person die in a bathtub and -- and lie about it. >> it was wxia reporter catie beck's report that brought the story to an atlanta both horrified and fascinated. she, who first secured access to all those police videotapes, exposing these pretty little liars for all the world to see. >> it suddenly becomes clear that these girls have multiple personalities, that they can be whoever they need to be for their own purposes. that they can morph between fragile, disturbed, innocent teenager into sort of this demonized criminal. >> those girls you knew, those sweet little girls. >> yeah. >> what happened to them? >> it's just hard for me to even -- i d't

>> and nikki's mom, lynda whitehead, carries the helpless grief with her every day, every sleepless night. without her daughter, without the granddaughters she thought she knew. >> i was so proud of them. and i knew -- and they would talk about what college they wanted to go to. i'm sorry. >> it's okay. >> so i'm sitting here, and everybody goes. >> that's an awful tough road. >> you can't even imagine because every morning i wake up, i think about my daughter and my grandkids. it's just a tragedy. >> one about a mother who dared dream that her sweet gemini twins would surpass her, who instead became their victim. that's all for this edition

of "dateline." we'll see you again friday at 10:00, 9:00 central. i'm lester holt. for all of us at nbc news, good right now at 11:00, disturbing new details on the death of a former nfl star. the suspect