Alissa Turney.Photo:National Center for Missing and Exploited Children

20/20 about the unsolved disappearance of Alissa Turney

National Center for Missing and Exploited Children

The stepfather “exhibited an apparent obsession” with 17-year-oldAlissa Turneybefore she went missing in 2001, police alleged in documents related to her disappearance.

There were the binoculars Michael Turney allegedly admitted to police he used to spy on his stepdaughter at work. There were the homemade contracts written between them — including one declaring that Michael had never molested Alissa, who he’d gone on to adopt. There were the surveillance cameras scattered inside their Phoenix, Ariz., home — and the cameras are the focus of tonight’s episode of20/20focused on Alissa’s still-unsolved disappearance, airing from 9:01 to 11 p.m. ET on ABC and tomorrow onHulu. (An exclusive clip is shown below.)

The20/20episode dives into the recent twists and turns of the case — complete with a false confession from a serial killer, the discovery of pipe bombs in the family home, and, finally, the dismissal of charges against Turney in July. (Alissa is presumed dead, but her body has never been found.)

Michael Turney.ABC News 20/20

Alissa Turney, Michael turney

ABC News 20/20

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At first Sarah hadn’t believed her father could be capable of murdering her sister. But, “for me, it was kind of like a switch,” Sarahpreviously told PEOPLE in an interviewfollowing her father’s arrest.

Alissa Turney.National Center for Missing and Exploited Children

20/20 about the unsolved disappearance of Alissa Turney

Believing him to be the reason her sister is “gone forever,” she campaigned to get her father behind bars, even secretly recording a 2017 meeting with him in which she urged him to tell her what really happened to Alissa.

“Be there at the deathbed, Sarah,” Turney told his daughter in the recording. “I will give you all the honest answers you want to hear.”

Michael Turney.Maricopa County Sheriff’s Office

Michael Turney

Butthe case was dismissed against Turney, his lawyers successfully arguing that the state had no physical evidence that Alissa was dead — or that Turney had killed her.

In an interview with20/20, Turney said that “the videos are recorded because I love my family, those are home videos that I’ve recorded since I can remember.”

When pressed about the security cameras stashed throughout his house, Turney said that “most of it’s for security.” He added sarcastically: “Why, because I want to spy on everybody?” He turned his head away and laughed.

20/20airs tonight from 9:01 to 11 p.m. ET on ABC and tomorrow onHulu.

source: people.com