The chief executive of Backpage.com is scheduled to be sentenced on July 18 in Arizona on a federal conspiracy conviction.
CEO Carl Ferrer pleaded guilty last spring to the federal conspiracy charge and money laundering charges in California.
His guilty pleas were made after seven others affiliated with Backpage were indicted on federal charges in Arizona.
Authorities say the classified site's operators ignored warnings to stop running advertisements promoting prostitution, sometimes involving children, because it brought in half a billion dollars.
In his plea in Arizona, Ferrer acknowledged knowing that a majority of Backpage's revenues came from escort ads, conspiring to launder revenues from the ads, and conspiring to sanitize ads by removing photos and words that were indicative of prostitution and then publishing a revised version of the notices.