Sony Computer Entertainment America (SCEA) does not know who stole data from nearly 75 million customer accounts on their PlayStation and Sony Online services, but they claim to have a hunch.

In an open letter to members of the U.S. House Subcomittee on Commerce Manufacturing and Trade, the chairman of SCEA claimed that forensic researchers have discovered a file that was "planted" on their systems by hackers.

He told Congress the document only contained a single sentence: Titled "Anonymous," it read, "We are legion."

That is indeed an Anonymous catch-phrase, but it is not entirely clear whether this can be blamed on the group, one of its members or someone trying to make it appear as if they were involved.