skylar's parents are besides themselves. their daughter is gone. can you imagine? it's evil. >> tonight on "20/20" -- unfriended. a popular teenage girl lured from home for a mysterious joyride in the middle of the night but she never comes back. >> i was scared to death. i didn't know where my baby was. >> does this creepy game by bffs recorded on a cell phone. >> would you rather suffocate or get shot. >> shot. >> drowning or suffocating? >> suffocating. >> tonight, "20/20" taking you inside a jaw-dropping mystery. >> it's a race against time at this point. >> and the secret world of mean girls gone wild. >> give me the phone. >> no. this is over. this is over. >> hurry up. >> from cryptic messages on

dpais and twitter to a real-life crime scene in the woods. >> skylar is screaming why. >> what happens when three's a crowd and one person gets cast aside. what secrets do they have and who do you believe when pretty little liars seem to be everywhere. >> her words were i have to tell you the truth about what happened last night. >> tonight, what can happen when you get unfriended. >> best friends from hell. there couldn't be a more fitting description. >> here now david muir and elizabeth vargas. >> good evening, a lot of you might have rung in the new year with a midnight toast but for one young girl, a midnight joyride was just the start of a mystery that devastated a small community. what happened to skylar neese. >> that's our question and to answer it we're taking you inside a massive search and social hot bed of high school where some of the most important clues are hiding on tweets enfacebook. facebook fights between bffs

were getting unfriended is just the beginning. here's ryan smith. >> reporter: they were 16 and inseparable. sheila, skylar and rachel. >> it was always those three together. >> you barely ever saw one of them by themselves. >> silly in their selfies. >> giggly teenage girls. >> they're pretty. they're sociable. this he's popular. >> but behind their smiles secrets that would shock everyone they knew. >> the level of deception, it's mind boggling. the police were just as shocked as we were. >> no one was expecting anything like that. >> pure evil. >> nestled in the green mountains of west virginia, the city of morgantown home to west virginia university known as a friendly family place. what's it like here in morgantown? >> it's peaceful. it's a small town that's growing really fast. nice people. >> reporter: dave and mary neese

live in star city. dave works at a local walmart, mary at a medical office. their lives wrapped around their only child, skylar. >> hey, gorgeous. >> hi, daddy. >> reporter: treasuring every spin. >> what a beautiful ballerina. >> reporter: every laugh. and every childhood memory. >> there was a time she had a tea party for me and after mary came home she noted that skylar couldn't reach a faucet and i had been drinking toilet water for the whole tea party. that was a good memory. >> at the time it wasn't a good memory. >> say, i'm a crazy girl. >> daddy is a crazy boy. >> reporter: she was daddy's little girl. >> i spoiled her beyond rotten. skylar was very loyal to her friends, the people she thought was her friends. >> reporter: when skylar was 8 years old she met another

spirited child with whom she developed an instant bond, her name is sheila eddie and they became thick as she was. >> if they weren't together they were on the phone together and that's literally 24 hours a day, i'm serious. you saw one of them you saw the other. >> reporter: what was your relationship like with sheila? >> have to turn away. >> she was like a part of our family. she was like one of our kids. >> the lemon burns. >> reporter: as a teenager skylar had a 4.0 gpa, part-time job at wendy's and active social life. in their freshman year they meet a striking redhead rachel, their duo becomes a trio. kelly was close to rachel. >> she called me her cool aunt. >> reporter: she was like a daughter to you. kelly says she was charismatic, popular and talented, cast casted the lead in the school play. on her 15th birthday she

introduced her to her new best friends sheila and skylar. here they are that night. >> two adorable little girls smiling up at me, you know, just looking so angelic. >> reporter: but that vision of angels would soon be shattered. july 5th, 2010, skylar finishes a night shift at wendy's. >> skylar walked through the door and gave her mom a hug and said i love you, mom. she hugged me and said, i love you dad. she went to bed. >> reporter: the next day dave and mary go to work. but when he returns home that afternoon, skylar's bedroom door is still closed. >> i knocked on her door. there was no answer. so i said, sky, come on, you got to get up and i till didn't get an answer. so i opened the door. i looked down at her bed and it hadn't been slept in and it scared me. so i immediately called mary. she said she's not home and i said, no. >> reporter: concerned his next call, sheila.

>> she answered on her first ring. i said you got any clue where skylar is? she said, no. i said when is the last time you talked to her? she said, last night about midnight. >> reporter: looking for clues in skylar's bedroom, dave discovers something out of place. when you came in here that day describe what thissing looked like. >> the screen was gone, completely and i found it in her closet and the window was open about that much so she can get her fingers up and lift it back up. i found a bench right here. >> reporter: outside the house dave points out where he saw a bench, a way for skylar to climb back foo her bedroom. >> i know she snuck out and she's not home. then i started freaking. >> reporter: it's now 4:00 p.m. and it's time for skylar's next shift at wendy's. skylar had never missed work but today she's a no show. >> wendy's called and said, is skylar coming to work today. i said, oh, jesus, mary said, call 911.

>> 911, do you have an emergency? >> i have a 16-year-old who snuck out of her room and has not been home, wasn't went to work. can't get ahold of her from any of her friends. >> has she done this before? >> no. >> reporter: just then mary gets a phone call from skylar's best friend, sheila. >> what did she say? >> her words were i have to tell you the truth about what happened last night. she proceeded to tell me that her, skylar and rachel had snuck out the night before and that they had driven around star city, were getting high and that the two girls had dropped her off at the end of the road because she didn't want to wake us up sneaking back in. >> i was scared to death. i mean, i didn't know where my baby was. it was horrible. >> reporter: sheila and her mother come over and offer to help in the search for skylar. >> we immediately went looking for her, gone door to door. and we just -- we couldn't find

her. >> reporter: but then mary remembers what will become a major key to finding skylar's whereabouts. >> mary said, oh, what about the surveillance? we got surveillance at our apartment. >> reporter: the surveillance camera intended to capture intruders instead reveals this grainy image of that night, a car pulls up at 12:30 a.m., 30 minutes after sheila says she dropped skylar back near home. minutes later skylar is seen sneaking out of the house. she slips into the car and disappears. what were you thinking when you saw her head flash on that screen and she's walking to that vehicle. >> for a second i felt relief because at least i know she didn't get abducted. >> it wasn't like she was pushed in. she willingly got in the car. >> what did police tell you? that they thought happened. >> they thought that sheila had dropped her off and skylar came back home and then snuck out again. >> reporter: for officer jessica colbank and corporal ronnie gaskins the video is their best

and only clue. what were you looking for. >> anything. trying to get pictures of the tires, rips, it's too grainy. >> that raised millions of other questions of who did she go with and where did she go. >> next, what happened to skylar? everyone has their own theory. >> got drunk and fell and hit her head. >> somebody maybe followed her home. >> she met someone on the internet. >> somebody is just too scared to tell us what really happened. >> stay with us. ♪ when you don't get enough sleep... and your body aches... you're not yourself. tylenolpm relieves pain and helps you fall fast asleep and stay asleep. we give you a better night. you're a better you all day. tylenol®

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>> announcer: "20/20" continues. once again, ryan smith. >> this is the last sighting of 16-year-old skylar neese. surveillance video outside of her home in west virginia. an eerie vision as she sneaks out of her bedroom, enters an unknown car and vanishes. >> surveillance video from the james place apartments show the 16-year-old girl willingly

leaving the xundz. >> a parent's worst nightmare. >> reporter: she seems to have left home voluntarily so police do not activate an amber alert. necessary ka colebank is assigned to the case two days after her disappearance. did you think it was a runaway case at that point. >> it does happen. kids run away and come home a couple days later. >> reporter: skylar's parents dave and mary are frantic. dave pleads on local tv for help begging his daughter to come home. >> we love you. come home as soon as you can, baby. honey, if you're scared, don't be scared. you're not in trouble. we need to talk and that's all, honey. just come home. >> reporter: each time they get calls with possible skylar sightings they rush into action. >> i would jump in my car and fly to the place they thought they saw skylar and go down to the supermarket and scream her name. i mean everywhere they thought they saw skylar, we were there. >> reporter: skylar's friends were worried but hopeful.

morgan lawrence has known skylar since they were 3 years old. >> i thought, maybe there was a fight, maybe there was something that made her upset and that shied's be back the next day. >> i thought maybe she just -- something happened at home. >> reporter: another friend writes skylar messages on facebook pleading with her to come home. >> hi, beautiful, i love you and i miss you. come home soon. >> reporter: the inseparable trio of skylar, rachel and sheila is now missing a key member. as for rachel, just hours after skylar's disappearance, she's happily posing for pictures on a boat with her family friend kelly kerns. but kelly says rachel is worried about her missing friend. >> i mean she was texting all the time. she seemed urgent. >> reporter: meanwhile, her other best friend is in constant contact with her parents helping them post posters and tweeting message, was really waiting for skylar to come home today. just days after her

disappearance sheila comes to the neeses' home devastated with a special request. >> she says, is it okay if i go back and sit in skylar's room for a minute -- for a few minutes? >> she was crying, sheila was, crying pretty hard and she was sitting on her bed so i just sat down on the bed beside her and rubbed her back so i was trying to, you know, console her, make her feel better. >> she was going through the same thing we were going through, just at a smaller level, you know. i mean, this is our baby that's gone and we're flipping out and she's her best friend is gone. i mean it's horrible. >> reporter: days turn into weeks and till no sign of skylar, no activity on her cell phone or bank card. and her parents doubting the runaway theory. >> she didn't take her cell phone charger. she didn't take her contact lens solution. >> apparently she was planning to come back fairly quickly. >> reporter: in tight-knit morgantown people are searching for skylar and wondering what

could have happened to her? like local crime writers jeff fuller and daylene berry. >> lots of rumors floating around, got drunk and fell and hit her home. >> somebody followed her home. >> reporter: and a possible break in the case. two bank robberies in nearby blacksville. corporal ronnie gaskins learn rumors that money was used to buy drugs for a local teen party. >> skylar had supposedly overdosed on heroin, she died and panicked and disposed of the body. >> reporter: where did that take you. >> we weren't coming up with anything. >> reporter: the last two people to see skylar had nothing to add to their story. they picked up skylar at 11:00 p.m. took a joyride through the winding back roads of rural star city, smoked pot, then dropped her off before midnight. >> very often the last person to see the victim alive is looked at with great suspicion. in this case, the girls' story

seemed relatively innocent. so police had no reason to believe both of them were lying. >> reporter: but for officer colebank, it's the small unspoken signs that make her suspicious. take me back to that moment where you go to speak to sheila. >> complete blapg on emotions, there was absolutely nothing. it was like iced over. it made me uneasy. >> reporter: colebank's meeting with rachel, the high school drama school also strikes her as odd. >> she was really nervous. >> reporter: which has got to be a red flag. what does she have to hide? >> their stories were verbatim the same. no one's story is exactly the same unless it's rehearsed. and she's annage stress so she can memorize lines. i'm sure they had it written down somewhere, okay, this is our story. we've got to stick to it. everything in my gut was sheila is acting wrong. rachel is scared to death. >> reporter: but police don't know what rachel and sheila are hiding or why.

meanwhile, skylar's parents are grasping for any clues taking a closer look at the bad influence sheila had become on their daughter. >> sneaking out at night, you know, found some marijuana in skylar's pocket one time. here it was sheila's. >> we didn't like the way sheila acted a lot of times but being she was skylar's best friend we kind of overlooked it. >> reporter: it's becoming clear the smiling face of skylar's bff was such a father said. you started interviewing people about sheila. how would they describe her. >> shady, sketchy, sneaky and pretty manipulative. >> skylar's friend morgan says sheila rubbed her the wrong way. >> she was very self-centered. she would almost do whatever it took to kind of get her way. >> reporter: amarette says skylar confided her there were cracks in the cliques. her best friends were snubbing her. these pictures she posted on

meet me suggest skylar had become a third wheel. >> she just thought that they were becoming closer so they were just pushing her out. she was really upset about it. >> reporter: the slights were sometimes subtle but clear as day for skylar. >> they would dress the same and both wear dresses or cares but they wouldn't tell skylar and they would say it was more like a coincidence but i secretly think that they planned it. >> reporter: are sheila and rachel hiding a secret about what happened to their best friend. officer colebank is determined to find answers to bring the neeses' daughter home. >> i promised them, i'm a bulldog in my investigations. i said i don't care if it takes me ten years to find the truth, i will eventually find it. >> reporter: next, the girls play a strange and secret game captured on camera by skylar. >> drowning or suffocating? >> suffocating. >> where would it lead? stay with us.

>> so do you think those girls, skylar's bffs are hiding something and if so, what is it? >> we're live tweeting throughout the show. use #abc2020. elizabeth and i will be right back. ♪ ♪ ♪ the evolution of luxury continues. the next generation 2015 escalade.

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"20/20" continues with "unfriended." here again, ryan smith. >> police begin to suspect that sheila and rachel are lying about what happened the night she vanished. the first red flag, tension in the relationship. officer jessica colebank pours through her facebook and twitter posts. what she finds sets off alarms. >> you could tell she was mad at

someone. >> in the weeks before she vanished skylar had posted angry messages, there's just something about you i can't [ bleep ] stand. people can be so mean for absolutely no reason. hope you don't expect me to give a [ bleep ] anymore. #bye. and the final tweet she wrote, sent 10:48 p.m. the night she disappeared. you doing [ bleep ] like that is why i will never completely trust you. >> she didn't trust someone. that was the issue and perhaps the most suspicious posting the strange game among best friends. sheila asks rachel and skylar how they prefer to die. >> would you guys rather suffocate or get shot. >> shot. shot have drowning or suffocating. >> suffocating. >> it's almost the same thing. >> i know but it's not. >> and when police reveal their cell phone messages they notice a curious absence. >> there was no mention of skylar whatsoever. it's as if she just erased it

from her mind forever. >> skylar has been missing for months. despite her parents' concerns about sheila's bad influence they're convinced that sheila is simply grieving over her lost best friend. even as the police say they have suspicions about sheila you were thinking, hey, back off of this girl. >> i even told them i said will you please leave her alone. i said those girls just lost their best friend. would you chill out on her for awhile? >> but the neeses don't know, gaskins and the fbi who have taken the lead on the case are finding actual evidence of the girls' deception. >> state police. >> sheila and rachel told police their joyride with skylar was contained to the star city area. desperate for complus police scoured surveillance video from local businesses, it paid off. this video captures sheila's car at 1:39 a.m. heading north away from star city. >> that was the first variation

if their stories is where they drove around. >> and there's not just video, cell tower pings from that night place them in the back woods town of blacksville. >> that just blew their whole, oh, we stayed in star city. you're 45 minutes away from where you're saying you're at. you can't do that. you're not houdini. >> so you say, aha, we have this information. what happens when you speak to rachel and sheila? >> they change their story to fit, oh, sure, we were in blacksville. i forgot that. oops. >> their carefully rehearsed stories are now mismatched. sheila, the high school drama queen claims skylar didn't join them for the ride to blacksville but rachel, the high school drama star says she did. they're starting to differ at least from rachel's perspective it sounds like the actress is starting to forget her lines. >> oh, yeah, she had to come up with her own lines and that's where she really started tripping up. >> once you start seeing inconsistencies in a story, it's all over. the person is lying.

and then you must ask the question why would they lie? >> sheila is adamant that her version of the night's events is true. she volunteered to take a polygraph. what did that say to you? >> arrogance. i think she thought she was smart enough to outsmart a machine. >> so she took the polygraph and what happened. >> failed miserably. >> rachel also agrees to take a polygraph, but en route on the day of the test she gets scared. jumps out of her father's car and flees. >> she jumped out of a moving vehicle to avoid it. if you haven't done anything wrong, why won't you take this test? >> now, armed with surveillance video and cell phone records that prove the girls have been lying, police tell dave and mary neese that skylar's best friends have a secret. >> that point we knew they had to know something. so we pushed. >> your mission is to try to get their secrets out of them. >> exactly. >> the neeses start posting

about karma on facebook writing that the girls need to tell what they know. classmates and even strangers are putting pressure on sheila and rachel. anonymous tweets like this one -- pretty little liars keep on lying. >> shield and rachel, you can't be part of the trio and not have any clue what's going on. >> kelly, close friend with rachel and her mother and hear the rumors she's stonewall. >> i get a text why isn't your friend's daughter cooperating so i send rachel a text. what the heck are you doing? >> even those closest to rachel are wondering, what is she hiding? >> i said, was skylar alive when you left her? yes! we didn't do anything to her. >> i think that in this situation, you cannot lessen the importance of peer pressure. >> reporter: rachel seems particularly affected. as the lead in that year's school play, she is accustomed

to adulation. >> it's like she was getting booed in her performance. it's that type of level of ostracizing her. she couldn't handle that. >> reporter: one night almost six months after skylar went missing, rachel cracks. apparently having a nervous breakdown. her mother calls 911. >> i have an issue with a 16-year-old daughter of mine. i can't control her anymore. she's screaming, she's running through the neighborhood. give me the phone. no, this is over. this is over. hurry up. >> oh, god, she just gave me a black eye. oh, god, hurry up, please. >> seemingly suicidal, rachel is admitted into a local psychiatric hospital. what happens there has never been revealed. but immediately upon release, rachel is driven directly to meet with police. >> she's nervous. she was shaking and the impression i got was, all right, now the truth is going to come out. >> next, you'll never believe what rachel tells police. >> this was something totally different than what you expected.

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>> announcer: "20/20" continues. once again, ryan smith with "unfriended." >> university high's leading lady rachel shoaf is it thought able to keep up the acronym. six months after the disappearance of skylar neese, rachel's abandoning the role of heartbroken best friend. and going from a psych ward straight into the interrogation hot seat. >> she's nervous. she was shaking. >> she's finally about to come clean to police about what really happened to her 16-year-old bff. it was a plot twist no one saw coming. >> the first words out of her mouth were we stabbed her. >> this was something totally different than what you expected? it took us a minute to settle down, okay, what do you mean you stabbed her? >> rachel tells corporal ronnie gaskins she and sheila began

plotting to kill skylar months earlier during science class. >> they're joking how they would dispose of a body then it got more sinister and need to figure out how to kill her. they didn't know how to use guns so used knifes. >> rachel wanted skylar dead now because she was about to leave for church camp, so one midsummer's night she and sheila gather critical tools, a shovel paper towels, wipes, a change of clothes and kitchen knives and arrange to meet with skylar. remember this grainy surveillance video? police couldn't make out the car. turns out it had been sheila's all along. 12:30 they arrive at skylar's house. the knives hidden in their hoodies. five minutes later skylar emerges. they drive out of star city past blacksville and across state lines to pennsylvania and into the woods of a town called brave where skylar is about to face the fight of her young life.

and they're driving on this road that we're on right now. >> yes. >> and skylar is in the backseat having no idea what's about to happen. >> she has no clue. >> gaskins takes me back to the murder scene. >> man, this is dark and creepy. i mean -- >> just imagine these girs are out here after midnight. >> and recounts what rachel confessed. >> all three girls exit the car. and they walk down this road. >> the girls find a grassy area to sit and smoke marijuana. skylar gets up and starts walking back to the car to get a lighter. that's when they execute their secret plan. sheila and rachel get up behind her and count, one sh, two, thr. >> then on three that was the time for them to start stabbing skylar. >> right here skylar is being stabbed by her two best friend. >> yes. >> skylar takes off running with her two friends giving chase. rachel tackles skylar and the pair continued to repeatedly stab their bff. >> according to rachel skylar is

screaming, why. >> then they try slitting her throat because they had read that it would kill her quicker if they cut her jugular. >> reporter: the plan was to bury her but the ground was too hard so instead, they drag her body to the side of the road and cover her with branches, rocks and leaves. they don't even bother to really conceal her. >> they change into clean clothes and wipe down the car and they left. like nothing happened. >> this was calculated, planned out, thoroughly thought of before this night. >> the perfect murder plot, everything planned to the tee, but why? >> and her only answer to that was we just didn't like her. what do you mean? we just didn't like her. >> well, why not. >> did you ever get the sense with rachel that she was really remorseful? >> she seemed to be relieved that the truth has been told. she doesn't have to hold it in any more and it's not eating at her anymore.

>> shockingly, even though rachel confessed, gaskins doesn't arrest her. >> we had no body. we had no physical evidence. i mean, we had all the circumstantial evidence, but we needed something more concrete. >> and there had been no cracks in sheila's armor so to try to nail her that night police put a wire on rachel hoping sheila incriminates herself but sheila doesn't take the bait. instead of two killers take this selfie together. finally got to see rach. then a break. police think they have an ace in the hole linking sheila to the murder. they find traces of blood in her car. >> we had to do a dna confirmation. >> meanwhile, rachel continues to give critical details to police. details skylar neese's parents so desperately await like the location of skylar neese's body. >> this area right here is where we were able to finally locate skylar's remains. >> she was one, two, three, four, five, six, maybe seven

steps away from the road. back in star city the neese family is holding a vigil on what would have been skylar's 17th birthday. they are finally told the news they had been dreading. skylar has been murdered. >> i was outraged. i was a mess. all these emotions running through my head at once. >> the search for monongalia teenager skylar neese is over. >> skylar was our world and now she's not here. >> soon the news breaks publicly. >> father, we thank you for joining us here today. >> but not the identities of the killers. and immediately sheila eddy takes to twitter to join the chorus of grief. worst day of my life. the pain is real and rest easy, skylar. you will always be my best friend. at the same time she is pretending to mourn online, sheila is brazenly taunting police, tweeting messages like, wonder if there's a law and order svu where they don't

figure it out and we really did go on three. a seemingly blatant reference to the crime but what sheila doesn't know is that authorities get their biggest break yet. conclusive evidence linking her to the murder. a dna match confirms that blood from the trunk of sheila's car is skylar's. it's that final piece that really nails sheila. >> that was news that i was waiting to hear. >> finally, with enough evidence to arrest sheila, gaskins closes in and tracks her to the cracker barrel where she is having breakfast with her mother. >> i just want to be able to get her right then and there, get her into custody. >> it's a race against time at this sflt we're not just dealing with a 16-year-old girl, this is a cold-blooded murderer. >> it's the end of the road for sheila. she is leaving just as gaskins pulls up cuffing her right there in the parking lot. >> i advised them she was being charged with the murder of skylar neese. >> what did it feel like for you to finally arrest sheila? >> just an amazing feeling. >> what did you say when you brought her to jail.

>> home, sweet home and then we shut the door with a big old grin on my face. >> case closed, but for skylar's parents, dave and mary. >> sicko. >> learning the killer's identities, not only brought more heartache and devastation, but also fury. >> they're acting like they really cared. and they're the ones responsible for the whole thing. >> casting devastating light on the moment when she was overcome with emotion in skylar's bedroo many. >> oh, my lord, we believed that garbage. >> can you imagine, your daughter's killer sitting on your daughter's bed crying and the mother putting her arms around her daughter's killer. >> skylar trusted those two witches and it cost her her life. with friends like that you don't want any enemy, that's for sure. >> how could they do that to their best friend? >> and the reason rachel gave that they just didn't like her?

>> that 's the biggest line of crap i've ever heard in my life. there has to be a reason. you don't do stuff like that for no reason. >> when we come back, the real motive? was skylar hiding something about her friends? did she know too much. >> skylar knew stuff about them that they didn't want out. >> her secret diary. revealed. the best part about working with quicken loans, is that you have a mortgage expert on the other line that's always gonna find out the best possible solution. we just don't treat you as a loan number. we wanna make sure that we help you out. we're people just like them. ya know, and we know that they have jobs, they have kids, they have soccer. their home is where their heart is. so we wanna make sure that we take care of them. call quicken loans today for a mortgage experience that's engineered to amaze!

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lifeand thankfully, of shaving stuff. being able to find backups. >> announcer: we return to "20/20." once more, ryan smith. >> she's a killer nobody would have suspected. the fresh-faced high school senior sheila eddy smirking in heir first court appearance. after months of secrecy the truth is revealed.

skylar neese's best friends, rachel and sheila were actually her worst enemies. the shocking news, they had lured her into the woods and brutally stabbed her to death. >> the search for skylar neese is over. >> rachel confessed. >> two teenagers implicate sfwld tore stabbing a third friend to death. >> many of skylar's friends hear about it at school. >> it devastated me. i actually had to get up and leave class. >> if you don't want to be friends with someone anymore, you just delete them on facebook like you don't go and get rid of them. >> kelly kerns has known one of the killers since the day she was born considering her like a daughter. >> when somebody tried to tell me they stab them, no way in heck. >> you couldn't believe that was your rachel. >> you can't tell me these girls stabbed her. and it wasn't until i opened the paper when i saw guilty and her picture. >> the picture. >> today looking at the photograph of rachel taken just

hours after she murdered her friend, kelly is floored by that smiling face. >> what strikes me about this picture is i don't see anything on her face that reflect what is she did. >> it just makes you feel, you know, what did you miss? >> and at the heart of the wrenching questions, how could two teenagers kill their best friend? >> they say they just didn't like her anymore. which is typical of teens, but teens typically don't kill each other when they fall out of like. >> i think it was because skylar knew stuff about them that they didn't want out. >> stuff, he says, that was hidden in skylar's diary where he says she wrote about a sexual relationship between sheila and rachel which she witnessed at a sleepover at rachel's house. daylene and jeff describe it in intimate detail in the new book they've written called "pretty little killers." >> they became involved

sexually. skylar was forced to watch because she knew if she left the bedroom they had all been drinking and would be in trouble. >> several weeks of s she said tell the whole school all the everyone which is a lot #ificouldgetawaywithit. >> just know i know. >> rachel and sheila had forred some type of a sex relationship that they believed skylar knew about it and would ultimately tell everyone. >> but the neeses say that skylar never would have acted on the veiled threats. >> she had a lot of gay and lesbian friends that didn't bother her. no, she didn't care if you were pink, purple, yellow, that was just skylar. >> why do you think they killed her? >> for the thrill of it. to see if they could get away with it. i feel that they had a strong dislike for skylar so it's fitting they stabbed her in the back. >> a year and a half after the murder, rachel faces justice.

she employeds guilty to second degree murder, a lesser charge based on her cooperation. finally in court she directly addresses the neese family. >> i am so sorry. i don't know if there is a proper way to make this apology because there are not even words to describe the guilt and remorse that i feel each day for what i've done. the person that did that was not the real me, not the person i am, not what i'm made of and not what i believe in. >> rachel's mom weeps as she listens. >> again, i'm so sorry and i pray each day for everyone involved and i pray each day for forgiveness. >> she can take her apologies and everything else and sit on them because that's about what they're worth. to me and my wife. she has done nothing but make our lives a living hell since this day one. >> she was crying. she was emotional. you didn't think that was remorse? >> to me that was her final act in front of an audience. she's the big actress, star of the high school plays.

this was her last broadway performance. >> at her arraignment a defiant sheila eddy pleads not guilty. >> sheila eddy, how do you plead. >> not guilty. >> but later she changes her plea. >> sheila eddy, how do you plead to the offense of murder in the first degree? >> guilty. >> guilty to first degree murder. she offered no words of remorse. why do you think sheila has never apologized. >> because she's not sorry. you don't apologize for murdering somebody in cold blood because she meant to do it. >> it's a good thing she didn't give an apology. people think it's horrible because she didn't? i commend her. don't stand up there and lie to me and tell me you feel guilty. >> rachel's family described her actions in a statement as unforgivable and inexcusable. sentenced to 30 years, she's now serving time in an adult prison. the same prison, in fact, where sheila, the girl she turned in

is now serving a life sentence. but both girls could be released on parole by their early 30s. >> if i'm dead and gone, somebody will be there to make sure they talk to the parole board and these animals don't get out of their cages. >> if you could say anything to sheila and rachel right now what would you say. >> rot in hell. >> skylar's friends are still trying to process their loss and mourn the milestones they are experiencing without her. >> skylar never got to go to a prom mary and dave never got to see her get all dressed up and get the bouquet and everything else. >> in memory of their only child dave and mary niece help pass skylar's law in west virginia that requires amber alerts for all missing children. >> this is skylar's room. >> when you come in here does it give you any sense of skylar now? >> yeah, it still does. >> they continue to treasure every item that belonged to

skylar. some of them don't mean anything. they were hers so we'll always keep them. >> she has a bunch of cards and drawings. >> yeah, see, her friends were always sending her a birthday wish for my friend. uh-oh. >> that's what i think of that one. that was from sheila, by the way. >> the card reads happy birthday, love sheila, bff. love you like a sister for life. for dave it's just one more reminder of the searing betrayal that has destroyed their world. >> because of that outward appearance, people don't want to believe they're capable. i still to this day have people say there's no way it's just those two girls. yes, it's those two girls. >> this crime to me is one of those crimes that go down in the books as truly evil. best friends from hell. there couldn't be a more fitting description.

>> today on a hidden road deep in the woods of a town called brave, there is a silent shrine. >> they say this is pretty much where she was found. >> the site of skylar's murder has been transformed into a memorial. on this visit a stranger had written a note to skylar. this one says, rest in peace, sweet skylar. soar with the angels. baby, i'm so sorry. if there's one lesson to be learned in here and one lesson only, know who your friends are. >> well, you just heard with good behavior the killers could be out of prison on parole by the time they're in their 30s. the question is, is that fair. >> let us know what you think, use the #abc2020. we'll be right back with

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aren't you a little bit curious? i just got my free credit score! credit karma. really free credit scores. really free. i have got to update my ink. since we first brought you the report dave and mary neese moved out of west virginia. it's just too painful to remain where skylar lived. >> they brought civil lawsuits against the girls and their mothers and we'll stay on the story. that is our program for tonight. thank you for watching. i'm david muir? and i'm elizabeth vargas. for all of us at "20/20" and abc news, have a good night and enjoy the rest of your weekend. >> happy new year. >> a heartbreak being conclusion

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