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(CNN) -- Brian David Mitchell, the homeless street preacher who abducted, raped and kept a 14-year-old Elizabeth Smart captive for nine months, was sentenced to life in prison Wednesday.
"We believe it is an appropriate, just and long overdue result for our community, for the Smart family and of course, most importantly, Elizabeth," said Carlie Christensen, U.S. Attorney for Utah.
U.S. District Judge Dale Kimball issued the sentence Wednesday. A jury found Mitchell guilty in December of Smart's 2002 kidnapping.
"Mitchell's heinous conduct, the evidence of his propensity to reoffend mandated such a sentence," Christensen said.
Beaming before a group of reporters gathered outside the federal courthouse, Smart, now 23, said she was "thrilled" with the sentence -- the maximum allowable under the law.
"As I said during court, and I'll say it again now, I absolutely 100% believe that Brian David Mitchell knew exactly what he was doing when he kidnapped me, and all the events that followed. ... Today is the ending of a very long chapter, and the beginning of a very beautiful chapter for me," she said.
Wednesday's sentencing occurred nearly nine years after Smart was abducted.
"This case demonstrates that the road to justice can be painstakingly long and emotional," James McTighe, the FBI special agent in charge of the case, said after the sentencing. "However, this case also demonstrates that justice will be served no matter how many days, months or years it may take."
Smart testified for three days during Mitchell's more than four-week trial.
"I felt that because of what he had done to me, I was marked," she said during her testimony. "I wasn't the same. My personal value had dropped. I was nothing. Another person could never love me."
She testified that she awoke to find a man holding a cold steel blade to her neck on June 5, 2002. She was taken from her bed and marched up a rugged mountain path in her red silk pajamas.
When they reached Mitchell's remote camp, Smart testified she was "sealed" to her captor in a marriage ceremony, raped and shackled between two trees with a metal cable. She said she was degraded and treated "like an animal."
Smart said she was raped nearly every day during nine months in captivity and forced to drink alcohol, smoke cigarettes and watch Mitchell have sex with his legal wife, Wanda Barzee.
She was forced to wear robes and a veil in public and was not permitted to speak to other people. She said she feared Mitchell would act on his threats to kill her and her family if she did.
She said Mitchell told her their marriage was preordained and that she would be by his side as he took seven times seven wives and successfully battled the Antichrist. They would hold exalted positions in God's new kingdom, she was told.
Smart told reporters Wednesday that she was determined to dedicate her life to child advocacy, "to help stop and prevent future kidnapping crimes, sexual crimes against children, against anyone."
She noted that the sentencing also occurred on National Missing Children's Day. Her father, standing beside her, held up posters depicting several children who were recently abducted.
"I think one of the biggest ways to overcome any trial in life, to heal from any kind of experience, is by helping those around you, because by lifting those around you up, you end up lifting yourself up as well," Smart said.