American computer hacker and co-founder of hacktivist group LulzSec, Sabu, is already an infamous name among the hackers of the internet.
Facing a combined 124 year prison sentence for his own activities, Monsegur turned himself over to the FBI the day following his arrest in 2011.
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Having turned informant for the FBI, the hacker, real name Hector Xavier Monsegur, aided the agency in tracking down and identifying other prominent members of the Anonymous network.
Now, documents uncovered by The New York Times (opens in new tab) have revealed that he may have been painting a target on other government's websites, particularly those of Iran, Pakistan and Syria.
The new documents show that Monsegur had been recruiting Anonymous members to do the US government's work for it, though it is unclear if this was at the FBI's request. The target list supplied by Monsegur to his recruits, according to The New York Times, contained more than 2,000 internet domains.
While working for the FBI he played a major role in the Anonymous attack on intelligence company Stratfor, his testimony secured a 10-year prison sentence for fellow hacktivist Jeremy Hammond.
In his work for the agency, Monsegur has also been involved in attacks on the Polish Embassy in the UK and Iraq's Ministry of Electricity.
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One expert commented that the documents were striking as it appears to show the FBI using hackers to feed information to other intelligence agencies.
"It's not only hypocritical but troubling if indeed the FBI is loaning its sting operations out to other three-letter agencies," said Gabriella Coleman, a professor at McGill University.