Dressed in a beige coat, the young woman walked quickly as she braved a phalanx of photographers and TV cameramen that would have flattered even an A-list Hollywood star. But this was no red carpet scene.

It was outside the courthouse in Salt Lake City and the woman was Elizabeth Smart, 23, plucked from obscurity and into national fame by one of the most horrific kidnappings in US criminal history. The story of that crime, which saw a 14-year-old Smart held captive for nine months and forcibly "married" to a man who considered himself a Mormon prophet, stunned America in 2002.

The bizarre details of the incident have finally emerged. Smart last week gave three days of testimony in the trial of Brian David Mitchell, a former street preacher who crept into her bedroom and spirited her away into the mountains at knifepoint.

All week Smart's story gripped Salt Lake City, dominating newspapers and TV shows, and was followed across the US. "There is tremendous interest about this case. It is every parent's worst nightmare: your child abducted in the dead of night. It's the script of a horror movie," said Paul Cassell, a law lecturer at the University of Utah.

Mitchell and his wife, Wanda Barzee, say they kept Smart prisoner out of a belief that God had ordered him to kidnap young girls to be his brides. Smart has told how she was raped almost daily as she was transported from Utah to California and back. At one stage they kept her tied to a tree and almost always lived rough in the mountains, setting up camps.

Eventually Smart was rescued as the trio walked down a suburb in Salt Lake City with their victim so traumatised she first denied who she was. But to some, the Smart kidnapping is more than just a horrific crime. It appears deeply tied up in the history and culture of the Mormon religion, whose founders came to Utah and Salt Lake City in the 19th century to escape persecution of their new and controversial faith.

For many, the brave, attractive figure of Smart represents today's Mormonism. Still deeply committed to her faith, she is resilient and was the perfect witness against her former captor. She comes from a family of hardworking Mormons, illustrating the church's reputation for strong families and high moral values.

Smart's face is one the church is proud to show off and her story of survival and enduring faith has been praised by religious leaders across the region. She is the perfect advert for one of the world's fastest-growing religions, one that is seeking ever greater political and social influence. It already counts Democratic Senate leader Harry Reid among its adherents and also Mitt Romney, the Republican former presidential candidate and likely favourite 2012 contender. Even Glenn Beck, the rightwing TV show host and conservative favourite, is a convert.

"It is a very driven, very well organised church that knows what it wants," said Jeremy Lott, editor of website RealClearReligion.org. "Mormonism is one of the most American religions and Americans are starting to see this. They venerate the US constitution, for example."

Mitchell's story echoes Mormonism's past as a new faith with radically different ideas from other offshoots of Christianity. He certainly looked like an Old Testament prophet with a grey-streaked beard and flowing hair. Each day in court began with him entering singing hymns, then being removed as he refused to stop. Like many of Mormonism's first leaders, he believed himself to be a prophet. His commitment to polygamy echoed that of Mormonism's founders, and though the church has long banned the practice many breakaway factions embrace it in small towns and isolated communities.

Even if Mitchell is insane, as his lawyers claim, his delusions have a very Mormon feeling with their talk of prophets, angels and taking many young wives, a strand of Mormon thought that church elders have spent more than a century trying to put behind them.

With her blonde, shoulder-length hair and a string of pearls round her neck, Smart detailed being shackled at the ankle and tied to a cable hung beneath two trees. She revealed how Mitchell threatened to kill her family if she escaped, something she said kept her captive more than any physical bonds. She detailed Mitchell's constant abuse, drinking and taking of drugs, all sanctioned, he said, by divine revelations. About the only moment of levity last week, that sparked a few laughs in court, was when Smart recounted how she once stopped Mitchell from raping her by pointing out he was meant to be spending time with Barzee. "One for the Smart team," she quipped in court.

"I thought no matter what happened to me my parents would always love me... so I decided I would live. I would do whatever he told me to. I would keep my life and my family's life intact and did that to the very end," she said.

That came after nine months. Smart's sister, who had seen her being abducted, recognised the assailant as a man who had done some work on their house. Mitchell was identified and spotted near Salt Lake City. Police picked them up and separated Smart from her captors.

She was wearing a wig and sunglasses and gave them a false name. But she eventually admitted who she was. "I was very scared. I knew the threats that I had been told for nine months... and at the same time I thought: this is it, this is it. I'm done. Like, this is over," she said.

Smart has moved on with her life, doing missionary work in France for the Mormon church, one of 52,000 missionaries in 180 countries. As such, she is typical of the Mormon mainstream.

Mitchell's stepdaughter visited him in jail last week. To her amazement, she said, he still believes Smart is his wife.