But charges of British police link Mr. Cleary to a group of hackers called Lulz, or LulzSec, which has been on a crime spree of the Internet in recent weeks, attacking Web sites and computer networks, including those of the Senate of the United States, the Central Intelligence Agency and Sony.
The British tabloids were quick to Mr Cleary, as the young criminal mastermind behind LulzSec, calling him a "Hack" the Lad "in titles on the front page of the cast. His mother, Rita, said his son is very intelligent, but has a history of mental illness, including agoraphobia. His lawyer, Ben Cooper, described Mr Cleary "vulnerable young."
Although it is unclear how much publicity it deserves, the arrest of Mr. Cleary made him a focus of public fascination with a wave of computer hacking cases, carried out by amorphous collective online.
Police say Mr Cleary is guilty of illegally using a computer to perform a denial of service — bombarding Web sites with so many automated messages that have closed. They say his targets were organisations including the British Serious Crime Agency organized.
In the hierarchy of computer hacking, the charges against Mr. Cleary and actions of LulzSec largely fall into the category known as hacktivism. Hackers are not motivated by money, but are primarily interested in protest or antagonize their goals, or in technical skills on display.
Hacktivists, according to computer security experts, are a different race from cybercriminals mainstream, seeking financial gain. These criminals, for example, manipulated the Citigroup Web site to steal personal information of credit cardholders.
The third category, say that experts are warriors, both working in the "cybercommands" governments like those of the United States and other countries, or for terrorist groups or mercenaries. They defend the computer networks, electricity networks and State secrets in his own country, while devising tactics to attack enemies.
Hacktivists tend to portray their activity as the sit-in digital, a form of protest. But security experts say that their actual attacks often cause damage to computer networks, and financial losses. LulzSec was more aggressive than most and most brazen in his choice of targets.
"This is organized crime that is typically distributed in several countries, said Mark Rasch, a former Justice Department Prosecutor, who is Director of security for CSC, a computer services company."It is a serious crime ".
The Thursday evening LulzSec released what it said were hundreds of internal documents from the Department of public safety to Arizona, including materials relating to counterterrorism and patrol operations. It says that it shall aim at the Agency because of anti-immigration policies of Arizona. A spokesman for the Department of public safety, Captain Steve Harrison, said the documents appeared to be genuine, but were sensitive, non-confidential.
Hacking was a mischievous young men — and are almost all men — because the computers were invented soon after. But the Internet has made an increasingly international pursuit. Power users of message boards online and chat software from the Internet, using these tools to communicate and organize activities became quickly the intruders.
"Hackers were among the first to understand the benefits of social networking," said Alan Brill, senior managing director of Kroll, a security consulting firm.
Hacker distant networks present a formidable challenge for law enforcement. But in recent years, they and prosecutors have formed their own international networks of communication, sharing information across borders. Arrest of Mr Cleary, for example, involved cooperation between Scotland Yard and the FBI
LulzSec, on a Twitter feed that you use to communicate with more than 250,000 followers, said that Mr. Cleary is "at best marginally associated with us." The Group did not respond to a Twitter message seeking comment for this article.
LulzSec, experts say, is a splinter group from anonymous, another line hacking collective. Anonymous is best known for his attacks in support of WikiLeaks, led by Julian Assange last year. The group went after the Web sites of companies such as MasterCard and PayPal, who had refused to process donations of WikiLeaks after it disclosed confidential diplomatic cables.
This year, said Barrett Brown, a former activist anonymous, "some of the most important leaders and hackers broke off and are now LulzSec."
The two groups of hackers certainly affect different poses. Declarations of LulzSec and his actions display a spirit of joy anarchist exuberant. Lulz, means essentially laughter mean-spirited and website LulzSec describes the group as "a small team of individuals who feel lulzy dullness of cybercommunity is a burden on what matters: fun."
The group is strongly antagonistic to the media. When a TV journalist for Russia today asked for an interview, she was told that he would be granted only if she and her producer wore shoes on their heads and wrestled in the mud while singing. They refused.
There seems to be much less joy in the anonymous culture. In a YouTube video that describes the group a voice intones: "there is no control, no leadership, only influence. The influence of thought ". Later, the video adds that the actions of anonymous have "brought justice to our world."
LulzSec Exploit have irritated others worldwide hacker who oppose its activities, particularly the exposure of the personal data of innocent Internet users. Those people are working to stop LulzSec investigates the identity of its members and providing information to the FBI
The LulzSec group, according to Mr. Brown, the former activist anonymous numbers between 5 and 10. Mr. Brown said members had faced — known by nicknames online as Topiary and Sabu — are mostly men in their 20s.
Mr. Brown said he had discussed with Mr. Cleary, and that he believed — contrary to the Declaration of LulzSec — who was involved with the group. But a person involved with anonymous, who declined to be named for fear of prosecution, said that Mr. Cleary was peripheral.
On Thursday, the Court decided to delay the application of Mr. Cleary for bail while police investigated.
Networks of hackers and their activities are murky by design, said Bruce Schneier, chief security technology officer of BT Group company. LulzSec, Mr. Schneier said, "is a badge, a name that is called each other, if you are one of the guys cool hackers now."
Riva Richmond contributed from New York.