A TEEN VANISHES WITHOUT A TRACE, BUT WAS SHE A RUNAWAY OR A VICTIM OF FOUL PLAY?, ON "PRIMETIME: CRIME," WEDNESDAY, AUGUST 12

In 2001, 17-year-old, Alissa Turney came home from school and was never seen or heard from again. Her stepfather, Mike Turney, told police that he drove her home that day and later found a note saying she was running away to California. He begged police not to treat her disappearance as a runaway teen, and spent years looking for her. The case went relatively cold until 2008, when convicted murderer Thomas Hymer confessed to killing Alissa. But what seemed to be a potential end of the case set off a whole new investigation. In following up on Hymer's claims, strange details began to surface about Alissa's stepfather, including unusual surveillance video inside the family home. Could Mike Turney have had something to do with Alissa's disappearance, or was she a defiant runaway? Turney sits down for the first and only time with John Quinones to answer some tough questions. The report, which also includes never-before-seen home video and documents, airs on "Primetime: Crime," WEDNESDAY, AUGUST 12 (10:00-11:00 p.m., ET) on the ABC Television Network.

When Alissa first went missing, the idea that she ran away did not come as a complete surprise for those that knew her well. She had a bit of a rebellious streak and, according to her best friend, Alissa often clashed with her stepfather's strict parenting style. But once the Hymer confession came, detectives discovered stories about a contentious relationship with her stepfather and the focus shifted to Mike Turney's involvement. And when a search warrant on Michael's home revealed an arsenal of guns, homemade pipe bombs, violent manifestos outlining a deadly suicide mission and thousands of hours of surveillance recordings, the case got even more bizarre. Does the uncovered material and new information from witnesses paint Mike as a devoted dad driven to the edge of paranoia over the search for Alissa, or is he a suspect in her murder?

David Sloan is the executive producer of "Primetime: Crime."