From Best Friends to Killers: Teens Murder Friend Because They 'Didn't Like Her'

— -- As high school sophomores, Skylar Neese, Shelia Eddy and Rachel Shoaf were inseparable.

Living in Morgantown, West Virginia, the then-16-year-olds were pretty and sociable, taking selfies and spending time together.

But everything changed on July 6, 2012, when Neese’s parents discovered she was missing. Six months later, Shoaf told authorities that she and Eddy had stabbed their best friend Neese to death.

At 16, Skyler Neese was thriving, according to her parents. She had a 4.0 grade point average, a part-time job at a fast food restaurant and an active social life.

She was Dave and Mary Neese’s only child.

“Skylar was a very bubbly person,” Dave Neese told ABC News’ “20/20.” “She was also very loyal to her friends, the people she thought was her friends.”

Skylar Neese met her best friend Shelia Eddy at age 8.

“She was like a part of our family. She really was,” Dave Neese said. “I mean, just like one of our kids.”

While entering her freshman year in high school in September 2010, Eddy met Rachel Shoaf. The next month, Eddy transferred to the same high school as Skylar Neese, and Shoaf also soon became friends with her. Before long the three teens began to argue among themselves.

On July 5, 2012, Skylar Neese went home after finishing a shift at work.

The next morning, her dad said he discovered that she didn’t sleep in her bed. He later found her window screen in her closet and a hidden bench that she could use to climb in and out of her window.

“Then I knew: she snuck out last night,” Dave Neese said. “And then, oh my god, she snuck out last night, and she’s not home.”

That same day, after Skylar Neese missed work for the first time ever, her parents called police to report her missing. Star City, West Virginia, police officer Bob McCauley responded to the 911 call and began investigating Skylar Neese’s disappearance.

Later that day, Sheila Eddy called Skylar Neese’s parents to tell them what had happened the night before.

“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 back off at the house,” Mary Neese told “20/20.” “The story was they had dropped her off at the end of the road, because she didn’t want to wake us up sneaking back in.”

Eddy said she and Rachel Shoaf had picked up Skylar Neese at around 11 P.M. and dropped her back off at home before midnight.

On the Neese’s apartment’s surveillance camera, a car is seen pulling up to the apartment at 12:30 A.M.

At 12:35 A.M., the grainy video shows Skylar Neese sneaking out of her room and slipping into the car, which drives away.

“I was scared to death. I mean I didn’t know where my baby was. It was horrible,” said Dave Neese.

On July 7, 2012, Shelia Eddy and her mom helped Skylar Neese’s parents canvass the neighborhood looking for her, while Rachel Shoaf left for Catholic summer camp for two weeks.

Two days later, the public learned that Neese was missing through television, radio and internet coverage. As weeks passed, the investigation into Skylar Neese’s disappearance continued. Police believed the most likely scenario was that Neese went to a house party and overdosed.

Corporal Ronnie Gaskins told “20/20” he heard rumors that Neese had supposedly overdosed on heroin. “She died. People there panicked, and they disposed of the body,” said Gaskins.