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Brian Thomas Mettenbrink of Grand Island, Neb., helped bring down the sites in January 2008 as part of the underground group Anonymous, according to court documents. Mettenbrink, along with other users, allegedly flooded the websites with so much traffic, legitimate users were unable to access the sites.
Anonymous, a loosely organized collection of Internet trolls, attacked the sites after a legal challenge over this Tom Cruise video posted on YouTube. In the video unofficially titled "Tom Cruise on Tom Cruise: Scientologist," the actor discusses, you guessed it, Scientology.
YouTube removed the leaked video at the church's request, which sent the trolls into a frenzy. Their anti-Scientology response, dubbed Project Chanology, included prank phone calls, DDoS attacks and general rabblerousing.
Mettenbrink, who now faces up to a year in jail, wasn't the only one to get busted. New Jersey resident Dmitriy Guzner, 19, pleaded guilty last year for his involvement in the attack. Guzner was sentenced to one year in prison.
Mettenbrink is expected to enter his plea next week in Los Angeles, say prosecutors.