April 16, 2001 -- 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.

"And once the door slams," Cook says, a cellmate told him, "'Take your clothes off.' Well, what am I gonna do? Who am I gonna call? Who am I gonna ask for help? I just endured it.

"This could go on for six months, seven months, maybe a year. Then he got executed or he moved out or something happened. Then comes the next one."

A 'Sexual Jungle'

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.

Texas prison officials say they take all complaints seriously.

"Bring us documented proof and we will investigate it," says Larry Todd of the Texas Department of Corrections. "I cannot imagine a correctional officer turning his head on an act of violence on an inmate."

But Johnny Vasquez, a former prison guard, says, "It happens all the time."

Vasquez echoes allegations of indifference made by inmates and activists across the country.

"Several responses that I can remember are, 'You need to grow some and defend yourself. Quit coming in here crying. Get out of my office. Don't bring this to me,'" says Vasquez.

"As far as the administration cares," says Rolen, "we're animals, we're thrown into a cage. We're to be kept there, whatever happens to us."

Sentenced to Torture?

Cook is now a free man with a wife and child. He was released from Texas' death row after getting a new trial.

"Even if I would have been guilty of the offense of murder, I don't remember the trial court reading to me that as part of my sentence was to go to the Texas Department of Corrections and be tortured … for 22 years," says Cook.

Tune in to World News Tonight Tuesday for the second part in this series on prison rape.