Just weeks after he entered the Texas prison system at age 19, Kerry Max Cook says he was gang-raped by fellow inmates. It was the beginning of what he describes as two decades of torture. More than 200,000 men are raped behind bars each year, according to the group Stop Prisoner Rape. While rape under any circumstances is a violation, human rights advocates say rape in prison is also torture. Cook, 46, now released from prison, says the first attack came not long after he ended up behind bars. They made me take my clothes off," says Cook. "They bent me over a concrete embankment that used to sit outside in the yard." Before it was over, the inmates had carved obscenities into Cook's backside. Over the next two years, he says, he was repeatedly assaulted and even locked up with his attackers. The American prison system has been described as a "sexual jungle," where there are predators and prey. Experts say some prison officials quietly permit rape as a way to control the population. "Where the predators " the more violent, powerful inmates " are in effect being given a bribe or a reward to cooperate with the prison authorities," says Harvard University criminologist Dr. James Gilligan. "As long as they cooperate, the prison authorities will permit them to have their victims." This may be why inmates such as Matthew Rolen say their cries of rape are simply ignored by prison officials. "They told me flat out: we don't care," says Rolen, 36, who is thin and nonviolent, which makes him a target. Rolen says he filed a series of complaints to Texas prison officials. They didn't intervene, he says, until an attacker beat him unconscious in a crowded dayroom.