Bloomberg is reporting that evidence collected by the FBI about Anonymous, which attacked websites of four companies to punish them for blocking contributions to WikiLeaks, will be considered this week by a U.S. grand jury, according to court papers and an informal spokesman for the group of activist hackers.

The federal grand jury in San Jose, California, will begin reviewing evidence tomorrow that includes computers and mobile phones seized from suspected leaders as prosecutors probe the coordinated so-called denial-of-service attacks in December, according to a federal subpoena and the spokesman, Barrett Brown. Anonymous directed activists to target payment processors MasterCard Inc., Visa Inc., EBay Inc.’s PayPal, and U.K.-based Moneybookers.com in public chat rooms.

Among the evidence seized by the FBI during multistate raids on Jan. 27 was data taken from an individual who controls one of Anonymous’s primary servers, identified by the organization only by his cyber-handle ‘Owen,’ Brown said.

“The FBI is breaking down people’s doors with guns drawn,” said Mara Verheyden-Hilliard, a member of the board of the National Lawyers Guild, which has talked with Anonymous organizers about their legal defense. “A group of people are engaged in a modern day electronic sit-in, and the FBI wants to treat that like it’s terrorist activity.”