(CBS/AP) STAR CITY, W. Va. - For nearly nine months, the people of this small West Virginia town saw the face of missing 16-year-old honors student Skylar Neese everywhere -- beaming at them from fliers on utility poles, in gas stations, even at the local tattoo parlor.
She had been missing since she slipped out of her bedroom window one night last summer, but some in this town of fewer than 2,000 people never believed she had run away.
Police chased numerous leads with no luck. The break finally came when one of Neese's friends admitted plotting with another girl to kill her -- shocking even the investigators working the case.
A newly released transcript of a secret plea hearing reveals that 16-year-old Rachel Shoaf said she and the second girl carried out a plan to kill Neese.
The two girls were charged with luring the straight-A student at University High School out of her family's apartment in the middle of the night, stabbing her to death at an agreed-upon moment and hiding her body under branches in a Pennsylvania township about 30 miles away from her house, according to court documents.
The pair -- one of whom has now pleaded guilty -- had spent time with Neese's mother after the slaying and even helped with the search.
The cold calculation and brutality of the plot shocked a community already frustrated by the slow pace and secrecy surrounding the case. Investigators have said little since announcing the charges three weeks ago. Court documents offer no insight into the motive.
Shoaf, a red-haired student actress and singer, pleaded guilty to second-degree murder in Monongalia County Circuit Court on May 1 and awaits sentencing in a juvenile detention center.
The other girl's identity is, for now, shrouded by the confidentiality of juvenile court. Though local barber BJ McClead says most people in town have figured out who it is, it's unclear how long the three girls had been friends or just how close they were.
It's also unclear whether prosecutors will try to have the second suspect charged as an adult, as Shoaf was.
Monongalia County Prosecutor Marcia Ashdown has refused to return repeated calls seeking comment.
The mystery began July 6, 2012, when Neese climbed out of her bedroom window. Surveillance video showed her getting into a car at the end of her street in a quiet residential neighborhood near West Virginia University. With no sign of fear, no money and no contact lenses, she apparently expected to return.
When she didn't, Dave and Mary Neese worried. Police initially suspected their daughter was a runaway, but they knew better. They walked up and down Crawford Street with Neese's photo, then plastered fliers everywhere.
For months, police chased down tips to no avail. The transcript from Shoaf's hearing shows the break came Jan. 3, when she finally told investigators the truth -- and where to find the body.
But it wasn't until March that authorities confirmed it was Neese, and silence followed until the day of the plea hearing.
"I think police who were involved in the front lines of that interview and that part of the investigation were stunned at Rachel Shoaf's confession," Ashdown told Judge Russell Clawges that day. "She confessed to a plan and conspiracy with another juvenile to kill Skylar Neese. A plan carried out."
The three girls drove to Wayne Township, Pa., got out of the car and the suspects pretended to socialize with Neese.
"And, at a planned and agreed upon moment," Ashdown said, the girls "attacked and stabbed Skylar to death, and they left her there."
They tried to bury Neese, she said, but covered her with branches when they couldn't.
In the five-page court file on Shoaf, prosecutors say they plan to recommend a 20-year prison sentence. But she could get as many as 40 years under the law.
Shoaf's family issued a public apology through a lawyer but has made no further statements.
"There is no way to describe the pain that we, too, are feeling," they said. "We are truly sorry for the pain that she has caused the Neese family, and we know her actions are unforgivable and inexcusable. Our daughter has admitted her involvement and she has accepted responsibility for her actions.
"Our hearts are broken for your loss," they told the Neese family, "and we are still trying to come to terms with this event."
Mary Neese has declined interview requests.
But the family has tried to spare others their agony, persuading legislators to pass "Skylar's Law" earlier this year.
Under the law, Amber Alerts are no longer limited to kidnappings in West Virginia. Even when authorities suspect a child is a runaway, information is turned over to Amber Alert officials.
The transcript of Shoaf's hearing shows other students also had suspicions, chattering on social media about all three girls.
A few overheard a conversation between the suspects about the plot but waited to report it. The teenagers thought it was a joke, Ashdown told the judge, "but only later decided and believed it was all too true and all too prophetic."
McClead marvels that two teenage girls could maintain their deception from July to January.
"Some of the criminals that are locked up for life aren't that hard."