The FBI is investigating the founder of a "revenge porn" website, where scorned lovers were posting nude photos and videos of their ex-partners anonymously online.

Officials would only confirm to "Nightline" that there was an investigation, but declined to comment further on any other details.

Hunter Moore, 26, used to run a website called IsAnyoneUp.com, which he told "Nightline" he had launched as a place for "public humiliation." On the site, users could upload sexually explicit photos and videos without a victim's permission, and include screen grabs of Facebook accounts and links to Twitter accounts. A section on the website also allowed people to comment on the photos and videos.

The site became so popular that Moore said he was getting nearly 5 million hits a month. But in April, Moore sold his website for less than $15,000 to BullyVille.com, a social website on which people can share stories about being bullied and seek help. IsAnyoneUp.com was taken down.

But before the website was shut down, Kayla Laws, a 25-year-old aspiring actress, said nude photos of herself that she took, but never distributed, surfaced on IsAnyoneUp.com. Laws claims her computer was hacked.

"To be seen on that website is like, breaks my heart inside," she said. "It ruins everything I've built up for myself. It's embarrassing to know that they've seen that photo of me and they know what I look like topless because of that site."

Her mother Charlotte Laws, who is a private investigator, said she was outraged and contacted the FBI after Moore refused to take down her daughter's photos.

"We first asked him, we sent him a cease-and-desist and a take-down notice, and he basically said 'screw off,' in so many words," Charlotte Laws said.

She said she convinced the FBI to launch an investigation into whether Kayle's computer was hacked.

"The FBI, I've been extremely impressed with them," Charlotte Laws said. "They're highly competent and extremely responsive."

Moore denied that he ever hacked anyone's naked photos.

Before IsAnyoneUp.com was shut down in April, Moore boasted to "Nightline" that he was a self-proclaimed "professional life ruin-er" and he had no scruples about hosting the website because the people on it were simply "characters and avatars and icons on a screen" to him and he wanted to take "full advantage of people's mistakes."

Moore also bragged about the multiple cease-and-desist letters and complaints he got from victims' lawyers, and said his typical response was either to send a dirty picture or a simple "LOL."

Just as YouTube hosts other people's videos, IsAnyoneUp.com fell into the same category -- the person submitting the picture accepts full responsibility for uploading it.

"Your only remedy is against the person who took the picture and posted it," said Bruce Johnson, an attorney in Seattle who specializes in First Amendment and media cases. "There's no real remedy against the website that's posting that photo. The best advice is not to disseminate the picture to begin with."

When BullyVille.com bought Moore's site and shut it down -- IsAnyoneUp.com's URL now re-directs to BullyVille.com -- it seemed that Moore had changed his tune. The site hosted a letter from him filled with words that sounded nothing like the rebel "Nightline" had previously interviewed.

"I think it's important that everyone realizes the damage that online bullying can cause," Moore wrote.

James McGibney, a former marine and founder of BullyVille.com, told "Nightline" he did a public service by shutting down Moore, something he said even the government wasn't able to do. However, several critics called the move a media stunt because the re-direct from IsAnyoneUp.com occurred less than a week after BullyVille.com launched, and BullyVille.com received two million visitors from it.

McGibney denied that shutting down IsAnyoneUp.com was for personal gain.

"Do you know what kind of base [Moore has], the subscriber base?" he said. "It's not the type of people I want on BullyVille."

But BullyVille.com isn't McGibney's only website. His bread and butter is CheaterVille.com, a website where anyone can accuse someone of cheating on a spouse or a partner and post it anonymously. But McGibney said CheaterVille.com is nothing like Moore's "revenge porn" website.

"There is no doubt I believe in what I'm doing or I wouldn't do it," McGibney said. "[CheaterVille.com] was not started for revenge or for malicious intent. It was designed to warn people, and I'm never going to change that thought because that's what I believe in."

Moore may have turned humiliation into a business model, but he hasn't cornered the market on getting even. Today, revenge is something he is trying to avoid.