Elizabeth Smart in 2013 (Photo: Getty Images)

During her nine-months of captivity, Elizabeth Smart, then 14, was subjected to unthinkable physical abuse and psychological manipulation. In a special interview airing on Friday, she tells Meredith Vieira how, during the ordeal, "she didn't' feel human." In 2002, Smart was abducted at knifepoint from her bedroom by itinerant street preacher Brian David Mitchell and held by Mitchell and his wife Wanda Barzee. "To her, I was a slave, and to him, I was an object," she says.

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At the moment of her kidnapping, she said her greatest fear was that her family would never know her fate. She wished he would rape and murder her by her parent's house so at least they would have some answers.

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The kidnappers took Smart to a secluded campsite about 18 miles from her home. Mitchell performed an improvised wedding ceremony and then raped her. Initially, he chained her to a tree by metal cable around her ankle allowing her only to reach a bucket she used to relieve herself. He would rape her, sometimes multiple times a day and drugged her and forced her to drink alcohol so she would be more submissive. Later, when the group was travelling in public, she explained she acted compliant-even when a police officer approached them, suspicious about her identity-because Mitchell had threatened to kill her family. In an interview with the Associated Press, she said, "For me, it was a life-or-death situation. There were days I didn't know I'd make it."

But, somehow, Smart did survive. After what she describes as being "ripped from my family, from my friends, from the people I loved," she says she prayed and tried to keep the sound of her mother's voice clear in her mind. In 2003, a biker spotted her with her captors after seeing Mitchell's photo on the television program "America's Most Wanted." She was rescued the same day. At a conference in July, Smart told participants how she began her road to recovery. "My mom said, 'Elizabeth, what this man has done to you is terrible, and there aren't words to describe how wicked and evil he is…but the best punishment you could ever give him is to be happy. Move forward and follow your dreams and do exactly what you want to do. …If you relive it, you're only allowing him to steal more of your life away from you.'"

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Later, in the aftermath of the Ohio kidnappings, she repeated her mother's lesson to the three survivors, "I would want them so much to know that nothing that anybody else can do to them will ever diminish their value," she said. "Each of us are born with value that will never leave for our entire life."

Ten years after her rescue, Smart's life and work are a remarkable testament to the power of human resilience. While her captors stripped her of her humanity -"I don't think there's anything worse you can do to a child," she tells Vieira-she was able to recover and, what's more, help others avoid the nightmare of what she bluntly calls her "nine months of hell." In 2011 she established the Elizabeth Smart Foundation to advocate for missing children and help prevent predatory crimes. In 2012, she started another chapter in her life, marrying Matthew Gilmour who she met doing missionary work in Paris.

The interview airs at 10 p.m. on NBC on Friday. Smart's memoir, "My Story" will be released on October 7.

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