Transcript for Undercover at a so-called gay conversion camp
We move to an ABC news investigation. Chief investigative correspondent Brian Ross takes us inside programs that claim to perform gay conversions and here with a preview of his "20/20" special. For the last year we've been investigating places that many claim no longer exist. Camps where gay teens are sent by parents who want their children to change their sexuality. So watch this video. Take a slight left turn on to rural road. Reporter: We found what we were looking for down a dirt back road in Alabama. The blessed hope boys academy. ??? Reporter: A place where a Christian pastor will tell our ABC news undercover team that with the bible and sometimes a belt -- You know, this boy here claims to be homosexual. Reporter: Along with a $21,000 yearly fee, he knows how to deal with teenagers who consider themselves gay. It's going against the word of god. It is not bib likely right. Reporter: And he told our team that he gets written permission from parents to strike their child if they act up. I wouldn't do it just because for one just because he says he's queer. Reporter: This is just one of a number of places discovered by ABC news in a year-long investigation practicing a notion denounced by leading medical groups gay teens can choose to change their sexuality. For every camp like this there are a hundred more that nobody knows about that nobody's exposing on TV. Reporter: Including one place outside mobile, Alabama, unlicensed and surrounded by barbed wire, run by this man, William knot who calls himself a Christian pastor but has a track record of physical abuse and cruelty. Everybody was scared of him. Reporter: Lucas Greenfield a gay teen from Florida was sent to knot's camp at the age of 14. Isolation and beating and everything else. Because? They were assumed to be gay. Reporter: Gay was a sin. Gay is a sin. Gay is evil. Gay is the worst abomination of god. Reporter: Karen was a counselor at the camp who says she quit when she saw how pastor knot treated the teens. Knot is a sadist. You think so. I know so. Anybody that has names for their belts to chip children with on their bare bottoms is a sadist. We saw how this Christian pastor reacts to someone he does not like. I'm with ABC news. What did you do to those boys? I don't want to talk to you. Because I don't like you. Get away from me. This is how you treat the young boys. This is how I treat you. Get away from me. Reporter: What that so-called pastor did not know when we met him was he was about to face his own day of reckoning in the wake of our ABC news investigation, six of the teens who said that knot abused and tortured them agreed to testify and just two weeks ago after being found guilty he was sentenced to 20 years in prison, the sentence the judge says in Alabama he hopes sends a message across the country. Wow. Names for his belts. Do parents know these things when they force their kids to go. Sometimes the cruelty only emerges after the parents leave but the parents sometimes have a hard time dealing with the sex sex sexuality and told with a bill of goods, the bible or belt they have a way to change their children. To one was more religious than my parents and I'm so grateful especially after seeing this how supportive they were of me as a gay woman and my family and friends and I'll never forget my mother saying, god loves you because of who he is, not because of anything you do or don't do. And I know you'll have much more. Essence of christianity right there. Love is love. More tonight on "20/20" and see how pastor knot treats those children.
This transcript has been automatically generated and may not be 100% accurate.