Alison Goodwin-Thresher, who has been missing since May of 2000. (Montgomery County Police Depart/Montgomery County Police Department)

For years, Hannah Thresher has struggled to overcome both an awful truth and an awful possibility.

The proven truth: Her teacher and babysitter, Fernando Asturizaga, molested, raped and sexually abused her for three years, starting in 1999 when she was 10.

The possibility: He may also have killed her mother.

“For my mother,” Thresher, now 30, said Thursday, standing in front of a bank of news cameras in suburban Maryland, “I need the whole truth to come out.”

At the news conference, police officials labeled Asturizaga a “person of interest” in the case of Alison Thresher, 45, who disappeared May 24, 2000. She was last known to be alive at her Bethesda apartment.

Detectives have never found her body or solved the case. They have long viewed Asturizaga with suspicion, according to records filed in Montgomery County Circuit Court.

Hannah Thresher, right, responds to questions following a news conference announcing a person of interest in the disappearance of her mother, Alison Thresher, in 2000. Sam Thresher, her brother, is at left. (Dan Morse/TWP/TWP)

Hannah Thresher spoke to help draw more attention to the case and publicly shared the impact of years of emotional and sexual abuse by Asturizaga.

He was convicted in her case after a 2012 trial where he was sentenced to more than 100 years in prison. Asturizaga, 51, remains incarcerated at the Western Correctional Institution in Cumberland, Md., state records say.

“I not only have justice for myself, which my mother would have wanted, I want justice for her, too,” Hannah Thresher said. “It would mean the world to me to find out what happened.”

She and her brother, Sam, have not been able to mourn over their mother’s body and never had a funeral for her.

“For us, it would mean everything, a chance to move on,” Hannah Thresher said.

It was not clear whether Asturizaga has an attorney.

The day on which Alison Thresher disappeared was supposed to mark a new start. She was set to start as a copy editor for The Washington Post. She never arrived at work. Her former husband, Jim Thresher, worked as a photographer at The Post.

On Thursday, Montgomery County Police Chief Tom Manger announced new details and findings in what police have called a homicide investigation, including that in 1999, Alison Thresher wrote to Asturizaga’s employer, Friends Community School in College Park, to tell the school of her concerns about his close relationship with her daughter.

She also confronted Asturizaga, Manger said.

Detectives now say they believe Alison Thresher may have been killed in her Bethesda apartment on Sangamore Road.

Law enforcement officials also said Thursday that on May 24, 2000, a neighbor heard cries coming from that apartment between 4 a.m. and 5 a.m.

A suspect or suspects also tried to destroy blood evidence at the scene, police officials said in the new appeal for public help on the case. A man matching Asturizaga’s description was seen running through Alison Thresher’s neighborhood, away from an area where her car would later be found, about 6 a.m., police said.

The details enhance a timeline detectives have worked with for 18 years and track to the 1990s, when Hannah Thresher was a student at Friends Community School.

Asturizaga taught Spanish and helped run an after-school care program and a summer camp that Hannah Thresher attended, according to a summary of the criminal case filed in the Maryland court system.

Asturizaga began to babysit her and her brother at Alison Thresher’s home when Hannah Thresher was in the fourth grade and at the home of her then-separated husband, court records show.

His abuse was planned, prosecutor Donna Fenton said at his trial, as he groomed her to trust him. “He twisted her mind and twisted her feelings,” and won her trust with gifts, Fenton said.

“My mother had grown suspicious of him and knew that our relationship was inappropriate, which she made known to both him and others,” Hannah Thresher said. “I strongly denied it when questioned as this man had carefully groomed me to do.”

As he spent more time with the girl, the instances of sex abuse increased, according to evidence during his trial. “He silenced her with fear,” the prosecutor said in court. “He silenced her with ma­nipu­la­tion. He silenced her with the range of emotions that this child experienced.”

The sentencing judge, Marielsa Bernard, agreed: “Hannah Thresher was such a vulnerable child, who trusted her teacher, her caregiver, a family friend.”

Yet Alison Thresher had her suspicions. “I write to you as someone who’s been a friend and great help to me and my family the last couple years,” she said in an April 1999 letter to Asturizaga. “Several times over the last several months I have expressed my concern to you that my daughter, Hannah, has formed an excessive emotional bond with you. When I made it clear that I did not want the two of you to be alone together, you assured me that you would, in fact, no longer babysit for Hannah and Sam. That was not true. And this led me to wonder whether this unnatural attachment is a mutual one.”

He continued to spend time around Hannah Thresher.

And her mother wrote in a journal about her ongoing worries about the teacher.

“Mad about my thoughts about F,” she wrote in March 2000. “Stress that lines of demarc’ he is a teacher.”

Two months later, on May 23, 2000, Alison Thresher had dinner with her parents, leaving their home about 8 p.m. Back at her apartment, she spoke by phone to a friend and at 12:17 a.m. May 24 sent an email to a friend. The email was her last known activity, according to a timeline provided Thursday by police.

After her mother’s disappearance, Asturizaga continued to prey on Hannah Thresher.

And he said something that only in hindsight seemed odd, Hannah Thresher said Thursday.

“ ‘I thought,” Asturizaga said, according to Hannah Thresher’s account, “things would be easier for us now that she’s gone.’ ”

On Thursday, as she appealed for help in solving what happened to her missing mother, she said, “This man took nearly everything from me — three years of my life, my youth, my innocence, my happiness and optimism for the future. But like others who have suffered, I am resilient.”

Detectives ask anyone with information about the death of Alison Thresher to call 240-773-5070 or 1-866-411-TIPS (8477). Callers may remain anonymous.