Jeremy Hammond, one of the five hackers arrested two days ago in the crackdown on key members of LulzSec and Anonymous, is no stranger to the law and has been described by his mother as "genius with no brain".

Court documents released earlier this week show that the 27-year-old Chicago native was arrested several times over the past few years for hacking activities, protests, mob action and other charges. The picture that emerges of Hammond is of an individual committed to a variety of activist causes with little concern about their potential consequences.

Hammond's latest arrest on the evening of March 5 occurred in what appears to have been a dramatic raid at the two-apartment building where he lives in Chicago. One of Hammond's neighbours who was interviewed on a local ABC news station described running out after hearing an explosion, and seeing about 30 FBI agents swarming Hammond's home.

Hammond was one of five individuals arrested this week in connection with a string of high-profile attacks by hackers claiming to be affiliated with Anonymous and splinter groups LulzSec and AntiSec. He is charged with breaking into computers at security intelligence firm Strategic Forecasting (Stratfor) last December and stealing account information on more than 860,000 Stratfor subscribers and credit card information on about 60,000 of them.

Sabu arrest

If convicted, Hammond faces up to 20 years in prison. A lawyer for Hammond quoted in the ABC news segment described the suspect as looking "shell-shocked" after his 9.30pm arrest on Monday.

Hammond's arrest by the FBI was facilitated in part by Hector Monsegur, also known as 'Sabu',' a former head of LulzSec who was arrested last July and became an FBI informant Monsegur engaged in numerous online chat conversations with Hammond. The transcripts of those chats were later used to make a case for Hammond's arrest.

Hammond's first major brush with the law was in 2005, when he was arrested for breaking into the website of politically conservative activist group Protest Warrior and stealing information on about 5,000 credit cards.

Hammond claimed he planned on using the cards to make donations to several liberal organisations though he ultimately never did. He pleaded guilty to one count of computer intrusion in connection with the 2004 incident and was sentenced to 24 months in federal custody and an additional three years of supervised probation. He spent about 18 months of that sentence in federal prison and was released in August 2008.

Hammond was arrested again in November 2009 for "violently protesting" a speech by a Holocaust denier at a restaurant in a Chicago suburb though it is not immediately clear whether he spent any time in prison on that charge. In November 2010, Hammond was sentenced to 18 months probation for throwing an Olympic banner into an open fire in Chicago's Daly Plaza to protest the city's attempts to bring the 2016 Olympics to the city.

'Anarchist communist'

The FBI in Chicago has information obtained from another investigation that Hammond may also have been involved in hacking the website of a white supremacist group, the complaint filed against him in connection with the Stratfor hack, alleged.

Transcripts of chat conversations between Hammond and other hackers suggest that the Chicago native was not shy about his run-ins with the law. The complaint against him has several examples where he is caught chatting with others about being arrested during the Republican National Convention in 2004, spending two weeks in county jail for marijuana possession and of his time in federal prison in connection with the Protest Warrior breach.

On more than one occasion he talks about his sympathy for left-leaning groups and anarchist organisations, and in one chat, describes himself as an "anarchist communist". Hammond's chats also revealed his links with militant anti-racist groups.

Hammond also is a freegan, an individual who reclaims and eats food that has been discarded by others, as part of an anti-consumerist movement. "Dumpster diving is all good I'm a freegan goddess," he says in one online chat conversation with another alleged hacker. Federal agents conducting surveillance on Hammond reported seeing him going into dumpsters for food.

'Genius with no brain'

A profile of Hammond in the Chicago Tribune portrays him as an extremely bright individual with a penchant for messing around with computers. As a student at Glenbard East High School near Chicago, Hammond allegedly broke into the school's computers to show administrators how vulnerable they were, and was thanked by administrators for the effort.

An effort to do the same while he was a student at the University of Illinois in Chicago got him expelled and may have spurred his transformation from helpful hacker to cyber vigilante, according to the Tribune.

Federal agents maintained a painstaking surveillance on Hammond's home for about a week before they moved in to arrest him two days ago. They obtained a court order authorising them to use a so-called Pen/Trap device (pen register and trap and trace device) to secretly collect dialling, routing, addressing and signaling information from his home. The goal was to gather information that would conclusively show that Hammond was the sole person using the computers and network in his home.

In an interview with the Tribune this week, Hammond's mother described her son as genius with a 168 IQ but little wisdom. "I love my son, but he is a genius with no brain," his mother Rose Collins told the newspaper.