PHOENIX -- Alissa Turney was a bright, energetic high school student, but on her last day of her junior year at Paradise Valley High School she vanished.
First believed to be a runaway, police did little to find her, until years later when detectives uncovered a sinister secret inside Alissa's North Phoenix home.
3TV has obtained telephone and videotape conversations never heard or seen until now.
Only four years younger, Alissa's sister, Sarah Turney, always looked up to Alissa.
"She was my hero," Sarah said. "She was my big sister. Everything she did was really cool and I wanted to be just like her."
Just days after her junior prom in May 2001, 17-year-old Alissa vanished. As Sarah explains, "It didn't sink in for a long time that she wasn't coming back."
Classified as a runaway, police did little to find her. Sarah was frustrated.
"There was absolutely nothing in the beginning," she said. "No one interviewed me, no one wanted to know what my side of the story was and I lived there. I was part of the entire action and the police had never asked me about it until years later."
Detective Will Andersen picked up the case in 2007.
"The last person to see this child was her stepfather, Michael Roy Turney. He's where we begin," Andersen said.
In hopes of uncovering evidence pertaining to Alissa, Andersen served a search warrant on Michael Turney's Valley home. They ended up seizing a massive amount of explosives, rounds of ammunition, even homemade silencers.
They also discovered evidence that gave them new insight into Michael Turney. Police said he set up hidden cameras in and outside of the house to keep tabs on Alissa. According to police, he even recorded thousands of hours of phone calls.
In one conversation obtained by 3TV, you can hear Turney talking about Alissa, who was 9 years old. Turney is recorded saying, "Should probably have her spayed. How's that for a disgusting thought? I'm sorry, that's really gross to say about your own daughter."
When Andersen heard those comments, he told us, "There's clearly a wrath there, there's clearly anger and animosity geared specifically towards Alissa."
As for the video found on the hidden cameras, Sarah explains, "When she was with boys, we'd keep an eye on her to make sure she wasn't going too far. But I don't know if he was viewing it from a different room, I have no idea how he had that set up, I was just aware that they were there. And when she was gone, I made it clear, he was not going to do that with me."
But when Andersen requested the video from the day Alissa reportedly ran away, "Mike is the only one who says that child returned to that home that day. He does not provide us with the videotape that shows her coming home. He does not provide us the videotape that shows us her walking out the door with her luggage."
"I have never seen the tape, I would love to see the tape," Sarah said. "It sounds, it sounds pretty suspicious."
Tuesday night on 3TV News at 9pm, we explore what's on the tape from the day Alissa disappeared. The investigation takes more twists and turns. Everything from allegations of sexual abuse to reports of bondage. There is also a call to CPS.
For any tips regarding this case, contact the Phoenix Police Department Family Investigations Bureau Missing and Unidentified Persons Unit at 602-534-2121. Detective Will Andersen can be reached at firstname.lastname@example.org or Detective Stuart Somershoe at email@example.com.