Transcript for Former member of 'Incel' community speaks out about dangerous misogyny
Tomorrow is the day of retribution, the day in which I will have my revenge. Soon after posting this video to YouTube. Elliot Roger would go on a shooting spree in a California city of Santa Barbara, killing six and injuring many others. The attack, a form of revenge by an angry young man, one who was hell bent on blaming women for his own personal loneliness. Girls are not sexually attracted to me. There's a major problem with that. Major problem. That's a problem that I intend to rectify. More and more, male hatred against women is rising up through the hidden crevices of online forums and entering real life, allegedly the inspiration between the mass attacks in Santa Barbara, Toronto, and Tallahassee, Florida. And experts say one of the chief inch cue baiters of this violent misogyny is a subculture of men and some women who call themselves incels or involuntary celibates, who gather in online forums finding common ground, in hatred of themselves and anger toward the opposite sex. Women are evil. Women are cruel. Women are mean. The group name that you've probably never heard of before, incels or involuntary celibate. Reporter: Now a new bbc documentary, inside the secret world of incels presents a never-before-seen world. A lot of people have not heard of the term incels and have not heard about the incel community. It's something more people should know about, because there is a risk of violence from this Reporter: When the incel movement first began online in the late '90s, it was seen by many as a comforting resource, a place to belong for those who had no sense of belonging. Oh, whenever I see couples walking about, I'm happy for them but at the same time, I am so alone. It hurts a little bit. Forums can definitely be very supportive, having an online community to fall back on or to go to is definitely a source of comfort. Reporter: It's a space that jack Peterson sought out as a struggling teenager. I think what attracts men to the incel communities is feeling like they have no other place to go. If they're rejected by women, if they're rejected by men, the incel community is a place for them to congregate and find people to talk to for once instead of stay in isolation. Reporter: It was a world where he could freely post this No matter where I go, what I do, nobody values my contributions. Reporter: Peterson eventually became a moderator for one of the forums. He says violent talk and threats were not tolerated. If someone crossed the line into threatening what seems like real violence they'll be banned from the website. I know on numerous occasions there would be communication with the FBI to make sure that nothing actually crosses into reality, that it just stays a post on an image board or website. Reporter: But some say Rogers' attack in 2014 mark add shift from the community that lived online to one that for some erupted into violence in reality. Before Elliot Rodger, there were a number of online misogynistic communities operating. But Elliot Roger really flips the switch from a community that is angry online, operating within the digital space, to a community that has the potential to carry out real acts of violence. Reporter: His blind rage, targeting strangers, like promising student Katie cooper. Her parents left devastated. He attempted to get into one of the sorority houses with a tremendous amount of ammunition. Instead, out of frustration, he got in his car, drove around the corner and saw my daughter. My daughter paid the price. So we like to believe that that wrong place-wrong time scenario helped save 50, 60 girls' lives. So, you know, kind of a silver lining. And, you know, when you're in our position, you look for you know, wherever you can. Just last year, two copycats. A van mowed down pedestrians, killing ten people, and then at a Tallahassee yoga studio. Both attackers allegedly posted online that they sympathized with Roger. "Nightline" is choosing not to show you more of Roger's videos. But it's clear he's gained infamy through these forums. Shortly after the attack, he decided to leave the forum all together. I asked the owner to permanently ban my account. I left after the Toronto attack because I didn't want to be part of a community that supports violence even in a joking way. Reporter: But Peterson says most incels are not violent and that within the incell community itself, Elliot Rodger isn't taken seriously. People think he's perceived as a hero figure, but I think he's more kind of made fun of. Reporter: Adam jessle, the executive producer has been studying the incel community for years. In terms of the number of people who are at risk of carrying out the violence against women or some kind of physical harassment of women, that is very small number. In the case of, you know, violence and mass murder, you only really need one person to move from, you know, online hatred to real-world violence. Reporter: Although not the norm, his film does seem to uncover disturbing instances of simmering anger toward women, manifesting in real-world actions. I'm the catfish man. I catfish females. I'm a legend in the community. I'm a hero. Reporter: Catfish man, whose full face is never shown humiliates women on camera as a way to seek revenge. So bad, look at that. So fat. Reporter: The women, who he says believe they're there to meet a model from online for a date are instead met with verbal the harassment and intimidation. It's kind of like a victory for the incel community. All those girls that treat the me like . Catfish man was very alarming and very distressing. On the one hand, we wanted to show people that this stuff is going on. This stuff is out there. On the other hand, we were conscious that we were giving airtime to this guy. Reporter: The anti-defamation league is one organization that's been tracking incel communities and identified them as an emerging domestic terror threat. It operates in some of the same ways we see other extremist groups operate. Reporter: They say community cooperation is key to monitoring violent content. Tips have always been helpful for law enforcement, when someone may be strained. The tech industry, responsibility and every day people knowing they have a stake in this. Reporter: As for Katie's parents, they hope her senseless death helps society to be more vigilant. Our daughter died because some individual couldn't cope. Just couldn't cope. That's why she's dead. And his parents missed it. Anyone who was trying to help him missed it. His friends missed it, society missed it, but my daughter paid that's the bottom line. If you want to stop this from happening to other parents and other innocent children, you need to get to the individual, you need to find a way to reach them and help them and realize that suicide isn't the way out. Going out with a bang so you can make the news isn't the way out.
This transcript has been automatically generated and may not be 100% accurate.