At least 400 teenage boys have fled or have been kicked out of their communities along the Utah-Arizona border, forbidden from returning home.
Known as the "Lost Boys," they once belonged to a secretive sect known as the Fundamentalist Church of Jesus Christ of Latter-day Saints, which broke from the Mormon Church because its members wanted to practice polygamy.
The Lost Boys believe that polygamy is directly related to their exile.
John Jessop says he was kicked out of his mother's house at age 13 after running away for three days.
"It's hard," he said, "not being able to talk to my family at all, really. I think about it all the time. I actually have a hard time sleeping because of it."
Sam Icke says his father made him leave home after he got caught kissing a girl.
"He had no choice in the matter," he said, "because if he wouldn't, he would have the same problem that I had. And he really believes in this."
The man they blame for their plight is Warren Jeffs, who law enforcement officials say dominates every facet of life in the FLDS community. He enforces a dress code, chooses who marries whom and even controls the police.
While representatives of the fundamentalist Mormons insist they're only kicking out people who violate their moral code, prosecutors and former members suspect the real motive may be polygamy -- an effort to reduce the competition for brides.
"These guys know that to continue to live polygamy -- and at the level it's gone to the last few years, with a few men having 10, 20, upwards of 70, 80 wives -- it's obvious that a number of boys have to go," said Dr. Dan Fischer, a former fundamentalist Mormon.
"In order to exist in a polygamist society you have to have more women to men, your ratio of women to men has to be greater," said Tom Sam Sneed, one of the many "Lost Boys" who have had to find new homes.
Sneed found a job and a place to live with the help of best-selling author Jon Krakauer, who wrote "Under the Banner of Heaven: A Story of Violent Faith," a book about fundamentalist Mormons.
Krakauer is personally trying to track down Jeffs, who hasn't been seen since January and is now under indictment on charges that he tried to arrange a marriage between a 28-year-old man and a 16-year-old girl.
"He has made it pretty clear that he will not be taken alive," Krakauer said. "He answers to the laws of God; he does not answer to American law or state law."
Jessop wants to see Jeffs caught.
"There's been times I wish I didn't exist," he said. "I felt alone in the world."
But more important than bringing the sect leader to justice, Jessop says he wants to be reunited with his mother.
ABC News' Dan Harris filed this report for "World News Tonight."