For a small town, there was a whole lot of crazy here. Delusion, depravity. And a sheltered young woman, living her life on Facebook. She was good behind a keyboard. As long as she didn't have to do... See More
For a small town, there was a whole lot of crazy here. Delusion, depravity. And a sheltered young woman, living her life on Facebook. She was good behind a keyboard. As long as she didn't have to do it face to face. When she tries more than just friending people, things get ugly. I was a bad person. I was horrible. I went through a whole lot. The young couple she says bullied her. Oh, my god. End up dead. Caught in the cross hairs of a Facebook but I like to be there early. So, I was one of tker -- E thesfastowt-grgling asses company in the now. Already worth over $1 billion. Hat I would offer --D say I'll give you the $80,000 as a loan until I recoup $120,000, plus you give me 10% of the company. The house!the $80,000, but the cost back is much less than me. He wants $120,000 back, but the equity purchase amount that Huch higher. It's 10%. I'm putting more of my risk in the company's ability to pay me back. I'm saying I'll give you $80,000. I want $240,000 back. But you don' that nobody has met? Could it be her own mother or father? Or someone playing murderous mind games by just tapping on a keyboard? She may be operating on a fourth grade level, but she has a phd in manipulating. Why are you crying? We're done. But we're just getting started. Does mother know best? Seems like you're completely blameless or you're an exquisite liar. What do you believe? Good evening. Social media is supposed to connect people, but this involves everything from romance to revenge. What happens when fingers on a keyboard become a weapon. Here's Matt Gutman. Reporter: Drive up the winding mountain roads of northeast Tennessee and you'll find breathtaking views, stunning scenery. They don't call it mountain city for nothing. Everybody knows everybody. Everybody is related by blood or marriage to everybody else. They all go to the same churches. Reporter: The sign at the city limits would like to suggest this is a congenial community of 2,500 with its arms wide open. The sign welcoming people to mountain city says, a friendly hometown. Friendly to you? Uh, no. Reporter: Why not? Because I wasn't born and raised here. I didn't grow up here. People here do not like outsiders. Reporter: Jenelle potter could have used a good friend. Plagued with debilitating health problems since she was little, she's now a loner who spends most of her time inside this shuttered ranch house under the watchful eyes of parents buddy and Barbara potter. What kind of person is she? Good-natured, sweet person. She is not an angry person. Reporter: Naive, young, innocent? Yes, very naive. And she is young in her mind, more young than her age, I think. Reporter: And although she doesn't sound like it, Jenelle is 30 years old. Looks good, right? Reporter: Her room is filled with animals stuffed that stand in as friends. She doesn't work and doesn't drive, and she confides in us she's never been with a man. What were the rules? Don't be out past 12:00 at night. No smoking, no drinking, no partying. Stuff like that. Reporter: They are a god-fearing and gun-loving family. Even when they garden they pack heat. Mom Barbara had a job with Hewlett Packard. And dad Marvin potter, better known as buddy, was a former marine who served in Vietnam rescuing P.O.W.S. And later he says he served with the cia. Sounds like Rambo. I just saw him as a gentle giant. Reporter: But age has taken its toll. Both are now disabled, buddy even on an oxygen tank. But Jenelle's life support becomes social media. Where she was UND. It was a precision in and out quickly. Facebook. Facebook defriending that led to What a tangled web we weave when first we practice to decei deceive. Out to eat. Reporter: They even got her to rappel. These are pictures of the new fast friends at backbone rock, a local landmark. Sitting next to a scared Jenelle is Tracy's brother, Billy Payne, a jokester who likes the outdoors. Did you ever get the impression that maybe she liked Billy? That's what everybody says. She fell in love with bill, but I still don't see it like that. Reporter: Instead, Tracy tried pairing Jenelle up with someone else, introducing her to Jamie curd, an older man who's pretty handy with computers. The kind of guy who likes to wear shades indoors. Jamie was sort of rough-looking, you know, greasy. And she was neat. Reporter: So why did you think to set up Jamie and Jenelle? Jamie didn't have a girlfriend, and she really didn't have a boyfriend. They didn't look like they'd go together by no means. Reporter: Jenelle and Jamie became an unlikely item, hiding their relationship from her strict parents. He's at the potter house from time to time, supposedly to fix the family's P.C., but behind her parents' back, Jenelle and Jamie would steal time and a few kisses together, snapping these secret romantic selfies. You and Jamie got pretty serious at one point. Yes. Reporter: He gave you a cell phone so that you guys could talk without your parents being on the phone. Yes. Reporter: How often would you talk? Every day. Reporter: For long periods? For an hour, two hours at a time. Reporter: Now, take note of Jamie curd and all that clandestine canoodling. Because you're going to hear a lot more about him a little bit later. But even while she's with Jamie, Jenelle is still secretly pining away for that outdoorsman she met, Billy Payne. And right around that time something sinister is happening with her online relationships. She's being relentlessly cyber-bullied. Appalling, anonymous comments begin appearing on her Facebook page. What kinds of things were people saying about you? I was a bad person. I was horrible. Threatened to get raped. Reporter: Must have been pretty scary. Yes. I remember, I wrote, "Please do not write on Jenelle's Facebook." I begged them, "Please don't do this." Reporter: And Jenelle thinks she knows who it is, pointing the finger directly at one of her so-called Facebook friends, Billie Jean Hayworth. What was her relationship like with Billie Jean? Oh, she hated her. Reporter: From the get-go? Mm-hmm. She would call her all kinds of bad names. Reporter: There might be one other reason these two don't get along. Billie Jean is engaged to, guess who, the object of Jenelle's obsession, Billy Payne. And together, the loving couple have a 7-month-old baby boy. Friends say Janelle was so jealous she started spewing some online venom of her own. That she wished that bill and Billie Jean and that damn baby would die. Reporter: An all-out Hatfield and mccoy-like feud erupts on social media, pinning the two couples against each other. The cauldron is boiling.the reasons that your social world became the Yes. I have a lot of family pictures on there. Random pictures, dogs. Reporter: Selfies? Any selfies? Mm-hmm.nts have access to your Facebook? Did they monitor it? Yes, yes. Reporter: You're a woman in your later Facebook Ell W-- EP R:or R a bteut simple trip to the pharmacy would employee named herself to befriend the social misfit Jenelle. Sick and stuff. She gave me her phone number, I started calling her. I would go out with her to th I did bill first and then I think Billie did me. And I unfriended her. Reporter: But unfriending would only be the beginning. There's no pulse. They're white, they're dead. There's a baby involved. Reporter: When we come back, the young couple's house becomes a crime scene. My impression after, you know, the first week was, it looked like a hit. Reporter: Like a contract hit? Right. Reporter: Suspects in custody, and an investigation that leads all the way to the cia. It's so incredible. The story is simply unfathomable. Reporter: Stay with us.
This transcript has been automatically generated and may not be 100% accurate.