The Alissa Turney Case: What If You Thought Your Dad Killed Your Stepsister?

May 17, 2001 was the last day of school for high school junior Alissa Turney, who lived in Phoenix, Arizona, with her stepfather and siblings. It was also reportedly the last day her family saw the 17-year-old.

At the time, police reportedly classified Alissa a runaway.

But over the years, questions have come up about whether Alissa's stepfather, Michael Turney, may know more than he has revealed.

Michael said he picked his stepdaughter up from Paradise Valley High School for lunch, according to The Murder Squad podcast.

He later told "20/20 on ID" they argued because she wanted more freedom and she was "definitely upset" when he last saw her.

"I told her that as long as you're under my roof, you're going to have to check in with daddy because daddy is a nervous wreck if you don't," Michael told host John Quinones.

In the interview, he said the last time that he saw his stepdaughter was when he'd left her home alone, and she was "walking down the hallway, mad."

Michael’s daughter and Alissa’s stepsister Sarah said that on the day Alissa disappeared, Sarah had taken a class field trip to a water park.

"I don't remember anything unusual about his behavior," she stated. "But he was late, so I'd walked to a friend's house nearby, phoned him from there, and told him that's where I was."

When he arrived to collect her, Sarah told "20/20" that her father told her that her stepsister was not answering her phone. Michael then asked Sarah to call her stepsister, which she says she did — but got no response.

Michael and Sarah reportedly returned home, where she told "20/20" they found her stepsister's phone vibrating in her room. Sarah also claims she saw a note that appeared to have been written by Alissa that allegedly read, "Sarah, you wanted me gone. Now you have it."

The note reportedly explained that Alissa had left for California.

Michael reportedly went to the police department to file a missing person's report, but based on what he told them, police allegedly believed that Alissa was most likely a runaway.

Michael told "20/20" that he was frustrated because he believed that the Phoenix Police Department was doing "nothing," so he began posting flyers around town and doing his own detective work.

Michael allegedly claimed he received a phone call a week after his stepdaughter disappeared. He claimed the voice on the other end was garbled, but that it sounded like his daughter, and that it said something that sounded like, "leave me alone."

In defiance of Michael's claims, and her previous faith in him, his daughter Sarah has expressed on her Justice for Alissa blog and on the Missing Alissa podcast that she believes her father may have been responsible for her stepsister's death — and she describes him as obsessive when it came to monitoring Alissa.

Michael Turney reportedly married Alissa's mother, Barbara Strahm, in 1987 when Alissa was three.

Strahm had Alissa and another son from a previous relationship, while Michael had three boys from his first marriage. Sarah was their only child together.

They called their blended family the "Brady Bunch," and did not use the term "step" to refer to each other, according to "20/20."

In 1993, Strahm reportedly died of cancer. After that, Sarah alleges her father became much stricter with his stepdaughter.

"The relationship our father had with Alissa is commonly described by those who knew her as one closer to an abusive boyfriend rather than a fatherly figure," Sarah wrote on Justice For Alissa.

"He was extremely possessive, often sitting in the parking lot of Alissa's part-time job to ensure she was where she was supposed to be," she said. "He constantly warned her friends and their parents of how she was gullible and unable to take care of herself. He also required Alissa to sign behavioral contracts that included a clause stating that he never sexually or physically abused her."

Sarah has posted recordings of her father on YouTube, including one that purportedly shows him watching his stepdaughter at work in 2000.

In 2006, a self-proclaimed serial killer named Thomas Albert Hymer, who is serving a life sentence in a Florida prison for killing a 30-year-old video store employee, allegedly confessed to killing Alissa.

He reportedly told police he met her at a hotel, and strangled her after sexually assaulting her. Hymer claimed he then dismembered her body and dumped her remains at a recycling center.

Detectives interviewed Hymer but reportedly determined his version of events did not sound plausible. He also allegedly failed a polygraph examination.

Hymer was ruled out as a suspect, but the renewed activity in the case reportedly resulted in the authorities beginning to take another look at the case and the relationship between Alissa and her stepfather.

Investigators spoke to her friends, who allegedly told them Alissa had claimed her stepfather tried to sexually assault her, ABC News reported. Alissa also allegedly accused Michael of saying demeaning things to her, and, according to allegations made by one friend, tried to gag her with a sock.

Police reportedly discovered an extensive surveillance system at the Turney home that monitored activity both inside and outside the home. Michael allegedly told investigators he had the equipment for safety reasons, and not to surveil his children, according to ABC News. When detectives asked him about a surveillance recording for the day his stepdaughter disappeared, Michael allegedly told them he had reviewed it and found nothing. But police allege he never turned the recording over to them.

While already complex, the case took yet another strange turn in December 2008.

Sarah claims detectives called her on December 11 of that year and told her they suspect Michael may have molested his stepdaughter and could be responsible for her disappearance.

Sarah also claims police told her that her father had allegedly been hiding many secrets, including, she claimed, that she has yet another sister.

But she said that at that time, she could not believe her father could have done anything to Alissa.

"He'd never abused me," she told Mel Magazine. "He gave me, literally, anything I wanted. When they [police] told me they were going to raid the house, my first thought was, 'I have to get home and help him.'"

She added, "He was so outwardly kind and generous. He always helped our neighbors out. He gave to charity. He fixed people's stuff."

When investigators from the Phoenix Police Department raided and searched Michael's home, they got another shock.

Inside the home, investigators found, among other things, 26 pipe bombs, according to an FBI press release. Authorities also found high-caliber assault rifles and a document titled "Diary of a Madman Martyr," The Arizona Republic reported.

Investigators alleged Michael had planned to blow up the local International Brotherhood of Electrical Workers union hall in what they reportedly classified as a bizarre revenge scheme against the organization. Allegedly, Michael believed the group was responsible for his stepdaughter's disappearance.

He also allegedly wrote in his manifesto that he had killed two "assassins," according to court documents cited by The Arizona Republic.

Michael Turney received 10 years in federal prison, the Phoenix New Times reported.

Despite those charges, he has always maintained his innocence in his stepdaughter's disappearance. Michael has also repeatedly denied he ever sexually assaulted his stepdaughter.

In 2009, he reportedly denied being uncooperative during the police investigation and allegedly said he had not actually planned to blow up the union hall.

Police "were calling me every day, asking me questions every single day," he told ABC News. He explained he had weapons in his home because he planned to "take a shotgun and blow my head off."

He said, "You can't kill anybody with a pipe bomb unless you stick it … down their throats."

Michael Turney reportedly earned his release from prison in August 2017.

In 2010, Phoenix police detective William Anderson reportedly told the East Valley Tribune that he believed Michael is guilty.

"Alissa was under this guy's thumb since she was 3, and for him to sit back and show her no regard is despicable," Anderson told the publication at that time. "He needs to explain a lot of things."

Anderson pointed out that Alissa left behind her cellphone, a necklace her boyfriend gave her, and $1,800 in a bank account, which he said he believed is not indicative of a teen who was planning to run away.

At the time of her disappearance, police described Alissa Turney as being 5 feet 4 inches tall, 145 pounds, with brown hair and brown eyes.

Her friends and family have never stopped searching for answers.

Authorities have asked anyone with any information about Alissa Turney's whereabouts to call the Phoenix Police Department at (602) 534-2121 or to leave an anonymous tip by calling Silent Witness at (480) 948-6377.