What happened to Natalee Holloway?

It's been more than 14 years since the high school graduate's mysterious disappearance in Aruba made international headlines and left her family and friends heartbroken. But even though the prime suspect in the case, Joran van der Sloot, has never been charged in her death, Holloway's mother has no doubt he killed the high school grad.

“He's a monster,” Beth Holloway told ABC News' “20/20.” “I know that he was responsible for the demise of Natalee. And I'll never, never not believe that.”

»FROM 2017: Investigation into Natalee Holloway's disappearance leads to discovery of human remains

The woman returned to the Caribbean island this summer for her first extensive trip there in nearly a decade, and she shared how she's coping with the loss of her daughter in an exclusive "20/20" interview set to air in a two-hour special Friday night.

Beth Holloway recalled in the emotional interview how she faced van der Sloot, a Dutch national who was 18 at the time, just about 24 hours after the teen went missing and believed he was the one who held the answers to what happened to the girl.

Joran van der Sloot, right, reportedly was with Natalee Holloway the night she disappeared.

Credit: Pedro Famous Diaz

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Credit: Pedro Famous Diaz

“I thought, 'You're it,’ “ Beth Holloway told the network. “Did I know what was to come? No. But I knew that I was gonna hang onto him ‘til my last breath.”

Natalee Holloway last seen in 2005

Natalee Holloway, who is presumed dead, was only 18 when she and her classmates traveled to the tiny island nation to celebrate their high school graduation. She was last seen on May 30, 2005, leaving a bar in Oranjestad and getting into a car with van der Sloot and two of his friends. She would have turned 33 on Oct. 21.

Van der Sloot was never charged in the case, but he was convicted of killing a woman in Peru five years later and is serving a 28-year prison sentence in that country. While in prison, he has gotten married and become a father.

»FROM 2018: Man who claimed he buried Natalee Holloway killed trying to kidnap woman

His version of what happened that night in 2005 has repeatedly changed over the years. He initially said he left Natalee Holloway on the beach the night she disappeared and went home, but later claimed to have sold her into sexual slavery — before denying that story.

A mother’s agony

Beth Holloway, along with her husband and local police, spent days searching for Natalee across the island, but her body was never found.

“Every time I looked out at the ocean, I couldn't handle it. It just disturbed me greatly. Because it made me feel as if I was never going to get an answer as to what happened to Natalee,” Beth Holloway told ABC. “But I feel like I have accomplished a huge feat. ... I can come back now to Aruba. I can get in the water. ... It feels great.”

U.S. federal prosecutors in 2010 accused van der Sloot of trying to extort money from Beth Holloway by giving her false information about the whereabouts of her daughter's remains. He is expected to be extradited to the U.S. when he completes his sentence in 2038.