Federal agents shut down the classifieds website backpage.com in an effort to purge the internet of sites that enable illegal sex work and sex trafficking.
Law enforcement also charged one of the site's founders as part of a 93-count sealed indictment.
Backpage, similar to Craigslist, allows users to post ads in a variety of categories. But it's notorious for its "adult" sections, which authorities say is a thinly veiled cover for sex work and trafficking.
Adult ads were some of the only posts that cost money; the website generated $135 million in 2014. After Craigslist stopped hosting erotic services ads in 2010, Backpage's ad volume grew by 50 percent.
Backpage had already shut down its adult section as of January 2017, but internal emails allegedly show the site's operators were more interested in masking illegal activity than in reporting it to authorities.
In addition to consensual sex work, the site has been accused of being a haven for child sex traffickers.
A 2017 Senate report cites the National Center for Missing and Exploited Children, which said Backpage was involved in 73 percent of suspected child trafficking reports the group received from the general public.
Congress recently passed a law meant to fight online sex trafficking that allows authorities to hold sites like Backpage legally accountable for users' illegal activity.