Some of the images described in court filings involved children barely old enough for kindergarten. At the time, the site had more than 215,000 registered users and included links to more than 23,000 sexually explicit images and videos of children, including more than 9,000 files that users could download directly from the FBI. The Justice Department acknowledged in court filings that the FBI operated the site, known as Playpen, from Feb. In each case, the FBI infected the sites with software that punctured that security, allowing agents to identify hundreds of users. The operation - whose details remain largely secret - was at least the third time in recent years that FBI agents took control of a child pornography site but left it online in an attempt to catch users who officials said would otherwise remain hidden behind an encrypted and anonymous computer network. WASHINGTON - For nearly two weeks last year, the FBI operated what it described as one of the Internet’s largest child pornography websites, allowing users to download thousands of illicit images and videos from a government site in the Washington suburbs.
