WHEN A FACEBOOK "UNFRIENDING" LEADS TO MURDER ON "20/20"

Airing Friday, October 9 on ABC

Social media is supposed to connect people, not get them killed. But when an online feud erupted between Jenelle Potter and a newly engaged couple, Billie Payne and Billie Jean Hayworth, the young couple ended up dead. Potter, a 30-year-old totally dependent on her parents and still living in their home in the small town of Mountain City, TN, inhabited a twisted, social media-riddled world of her own creation, trolling social media sites like Topix and Facebook. There she created a different persona for herself, befriending complete strangers, engaging in many online relationships. But she also fueled hate, feuding with many online, the most bitter of these feuds with Billie Payne and Billie Jean Hayworth. Prosecutors say Potter had a crush on Billy Payne and openly agitated against Billy Jean. After the couple was found dead, what followed was an investigation the likes of which Mountain City had never seen - embroiling an entire family, and even a shadowy figure named Chris who claimed to work for the CIA. It is a twisted murder plot which lands not only Janelle, but both her parents, behind bars.

Matt Gutman takes viewers inside the diabolical plan on "20/20" on FRIDAY, OCTOBER 9 (10:01-11:00 p.m., ET) on ABC.

"20/20" is anchored by Elizabeth Vargas and David Muir. David Sloan is senior executive producer.