Transcript for Police Suspect Missing Teen's Friends of Hiding Something
? "20/20"'s unfriended continues. Once again, Ryan smith. Reporter: This is the last sighting of 16-year-old Skylar neese. Surveillance video outside her home in West Virginia. An eerie vision as she sneaks out of her bedroom, enters an unknown car and vanishes. Video from the apartment shows the 16-year-old willingly leaving the apartment. Reporter: She seems to have left her home voluntarily, so police do not activate an amber alert. Officer Jessica Colebank is assigned to the case two days after Skylar's disappearance. Did you think it was a runaway case at that point? It does happen. Kids run away. They come home a couple days later, parents find them. 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 are scared, don't be scared. You're not in trouble. We need to talk and that's all. Just come home. Reporter: Each time they get calls with possible Skylar sightings they rush into action. I'd jump in my car and fly to the place they thought they saw Skylar. I'd 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 that maybe there was a fight, maybe there was something that made her upset, and that she'd be, you know, she'd be back the next day. I thought maybe she just, something happened at home, she wanted to get away. Reporter: Amorette Hughes, 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, Shelia, is in constant contact with Skylar's parents, helping them post missing person posters. Tweeting messages like this, was really waiting for Skylar to come home. Just days after Skylar's disappearance, Shelia comes to the neese's 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, Shelia 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. 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. We're flipping out. Her best friend is gone. It's horrible. Reporter: Days turn into weeks, and still 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 geoff fuller and daleen berry. There were lots and lots of rumors floating around. She got drunk and fell and hit her head. Somebody followed her home. She'd met someone on the internet. Reporter: And then a possible break in the case, two bank robberies in nearby blacksville. Corporal Ronnie Gaskins hears rumors that money from the robberies was used to buy drugs for a local teen party. Skylar had supposedly overdosed on heroin. She died. People there panicked and they disposed of the body. Reporter: Where did that lead take you? We weren't coming up with anything. Reporter: Shelia and Rachel, the last two people to see Skylar, have nothing to add to their story. They picked up Skylar at 11:00 P.M. Took a joyride through the winding backroads 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 girl's 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 the first time. Just complete blank on emotions, and there was absolutely nothing. It was, like, iced over. It made me uneasy. Reporter: Colebank's meeting with Rachel, the high school drama star, 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 an actress, so she can memorize lines. I'm sure Ty 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 Shelia had become on their daughter. Sneaking out at night, you know. Found some marijuana in Skylar's pocket one time. Heard it was Shelia's. We didn't like the way Shelia acted a lot of times. But she was Skylar's best friend. We kind of overlooked it. Reporter: It's becoming clear that the smiling face of Skylar's B.F.F. Was just a facade. You started interviewing people about Shelia. How would they describe her? What was she like? Shady, sketchy, sneaky, and pretty manipulative. Reporter: Skylar's friend Morgan says Shelia rubbed her the wrong way. She was very self-centered. She would almost do whatever it took to kind of get her way. Reporter: Amorette says Skylar confided in her, that there were cracks in the clique. Her best friends were snubbing Skylar. These pictures that Shelia posted on the website meet me suggest Skylar has 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, they'd both wear dresses, or skirts, 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 Shelia 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 Dave and Mary the very first day that I met them, I said, 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 secret game captured on camera by Skylar. Drowning or suffocating? Where would it lead? Stay with us. So you do you think the girls are hiding? Let us know on Twitter, using
This transcript has been automatically generated and may not be 100% accurate.