On October 9, 2013, Zenya Hernandez didn’t think it was strange when her 14-year-old daughter, Abigail Hernandez, didn’t come home from school.

“‘She must be in a certain location,’ Zenya Hernandez informed ABC News’ ’20/20,'” Zenya Hernandez expressed. “‘She is most likely attending school alongside her companions,’ I immediately responded, well.”

Abby, also referred to as Abigail, along with her two daughters Sarah, were brought up in North Conway, New Hampshire, and had a contented life under the care of their mother Zenya Hernandez, who worked as a nurse.

“Abby has always been very compassionate and adored animals. She was an incredibly cheerful and joyful child,” Zenya Hernandez expressed.

Zenya Hernandez said that her daughter Abby, who was very athletic, hiked a lot together and loved classic rock. Abby, as a freshman in high school, also studied robotics and German.

“It was a great life,” Zenya Hernandez expressed.

That is the reason why Zenya Hernandez became concerned when Abby Hernandez did not respond to her mother’s text messages.

Hernandez Zenya expressed, “I became extremely anxious when I noticed her leaving,” stated the librarian afterwards, “and I need to go to school.” “I will be going to school,” I replied, “and I was fine with it.”

Abby Hernandez had never failed to come home before, her mother said.

Zenya Hernandez exclaimed, “She was struck by a vehicle. Who knows? Appendicitis. Sustained a leg fracture. ‘What if she had sustained an injury?’ That was my thought.” “They have not laid eyes on her. Consequently, I contacted the hospital.” (I’m) starting to feel quite panicked, to be honest.

However, Zenya Hernandez did not believe that her daughter had fled from home.

“It was illogical,” she stated.

And Abby Hernandez’s fifteenth birthday was only three days ahead.

“Zenya Hernandez stated,” She was extremely excited about it. “To invite friends over for enjoyable activities,” we were organizing a grand celebration.

On October 7th at 7 p.M., Zenya Hernandez had filed a report at the police station, stating that she was missing persons. The community became aware of Abby Hernandez’s disappearance when the news reached them, leading to speculation about whether she had run away from home or was facing personal issues.

Cloutier, in her science class, mentioned that two girls were taking selfies. She saw them for the last time in the dark place. However, Cloutier stated that Miranda, Abby’s best friend, did not witness the teenage girl being in that place.

“We desired to be foolish collectively,” Cloutier informed “20/20.”.

Within 48 hours, the FBI agents who were involved in the case became part of the small team of door-to-door investigators in the town of Hampshire, New England, in order to find Abby, who had gone missing.

Three days following Abby Hernandez’s vanishing, her birthday came. Instead of a festive occasion, there was a solemn gathering.

I am thinking about you and Sarah all the time, and I miss you both so much. Zenya Hernandez shared a message for her daughter in the media, saying “I am thinking about you and Sarah all the time, and I miss you both so much. Please let us know when you want to come back.”

At 2:53 p.M., She sent him an affectionate symbol. Her partner Jimmy Campbell was on the school bus messaging her while Abby Hernandez had been last spotted walking home from school. All they were aware of was that investigators were in urgent need of details.

Fourteen minutes later, at 3:07 p.M., Abby Hernandez’s cellular signal vanished approximately a mile away from her residence.

We closely examined the people who were closest to Joseph Ebert, the lead investigator in the “20/20” case at the New Hampshire State Police. We focused on the relationship they had with him. Specifically, we paid careful attention to the communications between Joseph Ebert and his girlfriend.

He stated, “the individuals involved in this crime were the ones who were really trying to find alibis at various locations and bank accounts, not just for a few weeks but for months.”

Ebert stated that authorities discovered Abby Hernandez to be highly focused on her family and having a close relationship with her mother.

“We simply did not observe anything that indicated to us that something she had done had resulted in her vanishing,” Ebert stated.

Ebert said, “Although it didn’t seem like it, she had significant belongings for a significant period of time away from home. When we looked at the photograph of her leaving high school and the video of her leaving high school, we started to really think about the things that caused us concern.”

After a month had elapsed, Zenya Hernandez expressed that she was experiencing difficulty maintaining composure.

She said, “I fell into despair. Life goes on, and it’s like being surprised by the sun rising in the morning, one of those things that are like tragedies about things. Everyone suspected me. It was a wrenching and soul-sucking experience, and I just drove on.”

Zenya Hernandez was consumed with the ongoing search, neglecting her daily routine tasks, such as picking up her mail, for weeks.

“I said that,” she mentioned. It was a bit strange, but I did catch sight of a girl who resembled her greatly and stepped out of my vehicle, and I pursued her on foot. I was constantly searching for her.

Upon reaching her mailbox, she discovered a letter from Abby Hernandez waiting inside.

Hernandez Zenya stated, “I cannot tell you where I am, but I miss you, Mom… Yes, I am alive. I apologize for not answering your questions and for not being able to see the reports on TV and in the newspaper. I can imagine that you love me and miss me more than I can comprehend, dear Mom,” she said. “I am also confused by some aspects of the language, and I am extremely happy and cannot believe it.”

“It’s her, but it’s not her,” Zenya Hernandez stated regarding the communication from her daughter.

The correspondence was dispatched 13 days following Abby’s disappearance and brought a renewed sense of optimism to the investigators.

“According to Deputy Attorney General Jane Young, it was unclear how she ended up composing that letter, but we were able to verify her DNA profile on the document.”

Ebert stated, “It was a genuine surprise. The objective of the letter was to communicate, ‘I’m fine. Now please give me some space.’ It seemed like …”

Authorities waited a month to release the letter because they were concerned that making it public could put Abby Hernandez in even greater danger.

Young said, “We had numerous distressing discussions.” Our correspondence had somehow managed to be intercepted by an unknown individual. She was aware that her captor posed a greater danger if they discovered she had been kidnapped.

The revelation of Abby Hernandez’s letter caused a rush to judgment in the community, swirling rumors and a torrent of speculation according to the high school teen, Cloutier.

“It was certainly a popular subject for gossip,” she remarked.

“[It was] heartbreaking, because for us that meant that maybe they’re never going to search,” Zenya Hernandez expressed.

Investigators exonerated Jimmy Campbell as a suspect, but still believed that Abby Hernandez was at risk.

Young said, “She was in a situation where the definition of kidnapping didn’t matter. She only had her clothes on her back. We knew there was money at her home. She didn’t drive. Especially a 14-year-old girl, people don’t just disappear off the face of the Earth.”

And in a breathtaking twist of fate, nine months after her vanishing, Abby Hernandez entered her family’s residence.

Continuously subjected to sexual assaults throughout her period of captivity, she was forcibly concealed within a storage container against her desires. As it transpired, she had actually been abducted. The individual who had taken her hostage coerced her into penning a letter to her mother, insinuating that she had voluntarily departed.

Nathaniel Kibby, the individual who had abducted her, pleaded guilty to seven serious charges, such as abduction and sexual abuse, except in the state of New Hampshire. He will be incarcerated for a duration of 45 to 90 years.

Abby Hernandez, who endured being held captive against her will, will speak about her experience in an exclusive interview with ABC News’ “20/20” on Friday, September 7th at 10 p.M.

“20/20” informed Abby Hernandez, “I’m considering discovering a slightly kinder alternative to keep you silent,” he suggested. “You know, something akin to what dogs wear,” he proposed, “I’m contemplating a shock collar.”

Abby Hernandez mentioned that her kidnapper had placed an electric collar around her neck.

She exclaimed, “Now you understand the sensation.” This statement surprised me. Gradually, I began to speak louder. Furthermore, he instructed me, “Alright, attempt to shout.” I vividly recall him placing it on me.

“He informed me, ‘Contact me, contact me Master,'” she stated.

Abby and her mother express optimism about the future, despite the distressing experience.

Hernandez Zenya expressed, “If it’s not always joyful, it’s still possible to survive even in the darkest times. Even in the most hopeless situations, there’s still a sense of hope. We want to acknowledge that the world is aware of senseless and horrible things happening.”

Tune in to the complete narrative on ABC News’ “20/20” this FRIDAY at 10 p.M. Eastern Time.