Hector Xavier Monsegur. Source: Guardian.
Monsegur, known as Sabu in hacking circles, was arrested and charged by the FBI on June 7, 2011, on the hacking charges, but agreed to cooperate with the American agency, reported the Guardian.
While working as the double agent his group, LulzSec, also hacked into the CIA and the Serious Organised Crime Agency. The FBI provided Monsegur with a phone and laptop.
Monsegur pleaded guilty to the charges which took place between December 2010 and May 2011 and also include attacks on Paypal, Visa and Mastercard as well as sites belonging to Fox News and Sony Music Entertainment.
He was due to appear at Manhattan Federal Court on Friday to be sentenced on ten counts of hacking, one of bank fraud and one of identify theft, but US prosecutors have put it off with no explanation or replacement date.
Together the charges carry a maximum sentence of up to 124 years, but he is expected to get a suspended sentence.