Leaked search warrants suggest Sabu wasn't the only LulzSec hacker who helped the FBI take down the infamous hacktivist group.

The unredacted search warrants for ‪Sabu‬ and ‪LulzSec‬ refer to involvement of three different informants in the investigation, at least two of whom it is implied were members of the organisation.

Information from both Hector Xavier “Sabu” Monsegur and another unnamed internal mole were instrumental in supplying information that allowed Feds to acquire warrants against other LulzSec and Anonymous suspects. The two informants are referred to in the documents as CW-1 (confidential witness-1) and CW-2.

Sabu started helping the FBI following his arrest in June 2011. The documents don't reveal the name of the second informant, but the Daily Dot suggests this party might have been subjected to arrest in Ohio in June 2011 prior to informing on British LulzSec member Ryan Cleary, as well as implicating Ryan “Kayla” Ackroyd in a December 2010 hack against Gawker.

A Twitter update from around this time from LulzSec denouncing "M_nerva" for helping the Feds supports this theory.

One of 12 leaked documents (PDF) provides justification for a search warrant against a Facebook profile, “lesmujahideen”, linked to Monsegur. At the time of the warrant on 7 June 2011, the Feds already had Monsegur's IP address, linking illegal actions online back to an internet connection in a New York apartment. Investigators made this crucial IP address link in April 2011, earlier than previously publicly suspected.

The leaked documents (here on pastebin) are mirrored here and through a Dropbox account here.

LulzSec, for those who need a quick recap, was an infamous hacking crew that ran riot across the web during its "50 days of Lulz" between May and June 2011. Its victims included Fox, Sony, FBI-affiliated security outfits such as Infragard and HB Gary Federal, the US Senate, the Arizona State Police, the CIA and the UK's Serious Organised Crime Agency.

Most targets were entertainment firms opposing file-sharing, information security outfits it wanted to embarrass, or law enforcement agencies. Tactics ran from basic website-flooding attacks to defacement and site redirection. In some cases the group published stolen data from compromised websites.

Monsegur frequently acted as the group's ideologue as well as directing attack campaigns. He was the main man in a group that was nominally leaderless. He has already pleaded guilty to 12 counts of hacking, bank fraud, and identity theft but his sentencing has repeatedly been delayed.

Three British members of the notorious LulzSec hacktivist crew and a hacker affiliate were convicted of hacking offences and sentenced last May. The youngest of the four avoided prison while the other three were sentenced to between 24 to 32 months behind bars.

Other related arrests and prosecutions have taken place in the US and Ireland.

Another hacking suspect – Jeremy Hammond (AKA Anarchaos), 29, of Chicago, Illinois, received a far tougher sentence. Hammond was jailed for 10 years for a hack on security intelligence outfit Stratfor that took place in December 2011. As many as 60,000 credit card numbers stolen as part of the hack were used to make fraudulent donations to worthy causes.

Monsegur, acting as an FBI snitch at the time, tried to persuade the hackers who carried out the raid to store emails looted from Stratfor on a server controlled by the Feds. Information coaxed out of Hammond by Monsegur led directly to Hammond's arrest. ®