Hector Xavier Monsegur, also known by his hacker handle "Sabu," was a model informant who worked around the clock to help the Federal Bureau of Investigation nab his fellow LulzSec hackers, according to court documents that were made public Thursday, reports The Wall Street Journal.
"Since literally the day [Monsegur] was arrested, the defendant has been cooperating with the government proactively," Assistant U.S. Attorney James Pastore said at a secret bail hearing on Aug. 5, 2011, according to a transcript released on Thursday. Monsegur even stayed up all night sometimes, communicating with his co-conspirators in LulzSec to help the government build cases against them, according to the transcript.
Monsegur was arrested at 10:15 pm on June 7, 2011, and placed under supervision by FBI agents shortly after that. His file was then sealed by a judge in order to obfuscate Monsegur's status as a government mole from his fellow LulzSec members, who were known to monitor public court dockets.
Prosecutors in the case said that Monsegur agreed to cooperate at "a significant amount of personal risk" to himself. Monsegur was closely monitored throughout the investigation with software that tracked his online activity and with video surveillance inside his home.
According to The Wall Street Journal, the information that Monsegur gathered while working as an informant helped federal agents thwart more than 300 attacks that were planned by other hackers. Additionally, charges were brought against six men as announced on Tuesday. Monsegur's identity as "Sabu" was publicly revealed after those charges were made.