Transcript for A Boy Named Lucas part 1: Teens who say they were sent away because they were gay
In three-quarters of a mile, turn left onto county road 87. I know we talked on the phone previously. Yes, ma'am. And you know that my main concern is that my son believes he's a homosexual. Take a slight left turn on to rural road. Reporter: We found what we were looking for down a county road in Alabama, the blessed hope boys' academy. Where's brother Gary? Brother Gary. I think he's in the office. Okay, thank you. ??? Reporter: A place where a Christian pastor will tell our "20/20" undercover investigators that with a bible and sometimes a belt he knows how to deal with teenagers who consider themselves gay. It's going against the word of god. It is not biblically right. Reporter: It is just one of a number of places discovered by ABC news in a yearlong investigation, some operating with brutality, and others with just therapy, practicing a notion denounced by leading medical groups that gay teens can choose to change their sexuality. For every camp like this, there are 100 more that nobody knows about, that nobody's exposing on TV. Reporter: Including one place run by men who call themselves Christian pastors with a track record of cruelty. These are not religious people, these are people using religion as a weapon against these kids for further abuse. Reporter: The first leads in our investigation came months earlier, from two gay teens who say they had been held against their will in so-called Christian camps or academies. One, a 16-year old boy who arrived in New York on a late night bus. Lucas Greenfield, telling us he had just escaped from one of the camps in the south. How are you feeling? Tired, really tired. Reporter: And the other teen, 17-year-old Sarah Gibert from a small town in Texas, who was sent to a Christian boarding school for counseling one week after she defied her parents and went to the high school prom with her girlfriend. Their beliefs told them that people who were gay would go to hell. And so I think that the thought of their own daughter not being with them in heaven was probably upsetting to them. Reporter: In the case of Lucas Greenfield, he was uprooted from Naples, Florida, which became his home after he was adopted at the age of 3. Lucas was raised in what he calls a Christian home, but he says he increasingly came to know he was gay, to his mother's great distress. Because she wanted me to change into more of what she wanted me to be, which was very Christian, very religious, almost like a perfect kid. Reporter: Lucas, trying to find a place where he could be accepted as gay, and Sarah, declaring her affection for a girlfriend in Texas, both had to face what many gay teens find, a religious parent who cannot deal with their child's sexuality. It's this fear, it's all motivated by fear of somehow disappointing god. Reporter: Susan Cottrell is the mother of a gay daughter. She works with other Christian parents to help them accept their children as they are. They send them to camps hoping to outsource the problem of their kids, and get help for their kid not to be gay. Reporter: Lucas' mother would not agree to appear in our report, but told us on the phone she was only trying to help her son. She eventually was like, "You know what? You're going to a program." Reporter: The first program where Lucas was sent was located outside mobile, Alabama, in the town of Pritchard. It called itself the restoration youth academy, surrounded by barbed wire. Since I've been at this program, I've come closer to god and my family. Reporter: For the outside world, the academy used testimonials to promote itself as a place for troubled youth of all kinds to turn their lives around with prayer and the bible. And god also intervened in our life really, really dramatically. Reporter: Now closed, other teens sent here, both gay and straight, say it was a place of torture and abuse, carried out by the so-called Christian pastor who ran the boys' facility. He claimed to be a straight homophobe, and he said that he would cast out every homosexual spirit in every single homosexual male and female. Reporter: Gaylin wheeler, one of the nongay troubled teens, says he was a witness to how Lucas and other boys who were gay were treated. They would try to preach to them about how homosexuality is a sin and everything. And if that didn't get through to them then they would resort to alternative methods, as they called it, isolation, beatings, getting whipped with a belt. I can't stop seeing their faces, hearing the screams. Hearing the crying. That's why I don't sleep at night. Reporter: Lucas was only 13 years old when he says his mother left him here in the hands of the pastor whose brutality would emerge once she left. He asked her, he's like, "Do you mind if we spank your kid?" And you know what she said? "Beat his ass." Reporter: And did that happen? Oh, yeah, it happened. Reporter: Even worse, Lucas says, were these so-called isolation rooms, where he and others were left for long stretches of time. I only got let out about once a day to go to the bathroom. And sometimes they wouldn't feed you the three meals they were supposed to. Reporter: This is worse than any prison in the country? Oh, yeah. Prisons have laws and things they have to follow. This place, it was unlicensed, nobody even knew it existed. Reporter: But it turns out someone did know it existed, this Pritchard police captain, Charles Kennedy, who drove out here after a call from the concerned parents of another boy, and discovered what he would call pure evil. I thought, "My god. He is here. Lucifer is here doing business in our city with these children." Reporter: 450 miles away, outside hallsville, Texas, this is where Sarah Gibert says she was also being held against her will, a Christian facility that claims it helps gay teens. Like Lucas, Sarah felt powerless to resist what her parents arranged. And I was kind of in shock for a minute. And then, I started yelling at them and I told them that they couldn't do this. Reporter: But they did, and she says she was told she would be kept here for a full year, unaware that someone was about to come to her rescue. Her own personal superhero, her cousin and TV star Jeremy Jordan, outraged that Sarah and other gay teens are sent away like this. You're telling them, "We don't accept who you are, and we want to cleanse the world of your kind."
This transcript has been automatically generated and may not be 100% accurate.