April 18, 2008 -- As the nephew of Warren Jeffs, the self-proclaimed prophet of the polygamist compound in El Dorado, Texas, Brent Jeffs says that he knows all too well the misery and heartache of sexual abuse inside the Fundamentalist Church of Jesus Christ of Latter Day Saints.
Brent Jeffs was a victim of rape and molestation at the hands, he says, of his uncle, Warren, who is currently imprisoned. In fact, it was Brent Jeffs who first filed charges of sexual assault against Warren Jeffs.
"The entire cult, as I would put it, is run by complete fear. Everything they do is run by fear. They control the women and the children all by fear," Brent told ABC's John Quinones.
As another long day at court is expected today and authorities try to determine what is to become of the 416 children taken from the El Dorado compound, attention has been focused on the abuse of young girls, but Brent says the boys were also in danger.
"When I was a little boy, around 5 or 6, just attending the regular Sunday school, even when my grandfather was the prophet at the time, behind closed doors, Warren was sneaking around behind and would come down and escort me down the hall and into the bathroom and molest me as a kid. Threatening me with eternal damnation if I did not do exactly what he said."
Brent says he didn't complain because he thought he "was going to be in trouble. I thought I'd burn in hell for saying something. That's why I kept it a secret."
He says it happened to many other young boys, including Brent's two brothers, who were either students of Warren Jeffs or who lived inside his compound. That's why Brent Jeffs has come from his home in Salt Lake City to Texas to testify against the leaders of the El Dorado compound.
He believes the compound's residents are in danger.
"The wives and the women in here may not show you that they know it, but they are. They're in great danger. Because all they're doing in here is they're abusing all these children and you, they're abusing the women, too. It needs to stop."
"The men in there that have brainwashed these women and children, have convinced them ever since they were babies that this is right. Because they think in their minds they have nowhere else to go."
"The children are in a safe place. I know it seems like a horrible thing right now to have the children separated from the mothers. But, the situation needs to be taken care of … The way things are in here is, you know, when they're all together they're not going to say anything, afraid of the other person telling the higher authority and them getting in trouble. I think when they're by themselves, they may say something."
As close as Brent Jeffs is to the temple of El Dorado, the leaders of his old church will not allow him inside its gates.
"I have hundreds of cousins. I have so much family in there, I know I do. I saw someone on TV the other day, my aunt. My mom's sister, my aunt, who I've know my whole life."
"What do you think should happen to the compound?" Quinones asked.
"You know, as I'm concerned, they can live there and have their own world. It's the abuse. The abuse needs to stop. The women and the children need to have their freedom to choose what they want to do," Brent said. "If they want to leave they can leave. If the women want to leave with their kids, they can. Or, maybe a man wants to leave with his family. It just needs to be like everywhere else. You cannot have this sexual misconduct with all these young kids and all this stuff going on in there. It's not right. It's illegal."
"Someone needs to stand up and say, 'this is wrong.' I'm going to do anything I can to help these poor kids and these moms, if they let me."
Tune in to 20/20 at 10 p.m. tonight to watch more of this interview. John Quinones will also take you inside the El Dorado compound to meet the people who are now running things there.