The suspected leader of the hacking group Lulzsec has pleaded guilty to carrying out high profile attacks on several companies.
Hector Xavier Monsegur had been charged with conspiracy to engage in computer hacking according to unsealed court papers filed in Manhattan.
Reuters reports that the charges were filed via "a criminal information".
The news agency says that suggests that the suspect - nicknamed Sabu - had co-operated with the government.
US law enforcement officers have said a total of five people were either under arrest or being sought.
Irish police added that they have arrested one man in connection with Lulzsec's activities and are holding him at a south Dublin police station.
The Press Association reported that police officers in Britain have also been involved in the crackdown.
Lulzsec, which is linked to the online activist group Anonymous, had claimed responsibility for attacks against eBay and Sony Pictures among others.
Last month Anonymous published a recording of a private telephone conversation between FBI agents and London detectives talking about Lulzsec suspects.
'Internal rift'
According to the court papers Mr Monsegur formed Lulzsec last May. It said he acted as a "rooter", identifying vulnerabilities in victim's computer systems.
Alongside other recruited hackers he is alleged to have attacked the US Senate, the cyber security firm Unveillance and the American media group Public Broadcasting Service (PBS).
Prof Alan Woodward, from the University of Surrey's department of computing noted that Lulzsec had been quiet since the middle of 2011 following an attack on Paypal.
"Judging by the level of activity this morning, where hackers have been pasting personal information about the person reported as having turned witness to implicate other hackers, it would appear that there is a considerable rift inside these groups," he said.
"The hackers are certainly acting as if they feel they have been betrayed by one of their own."
Trend Micro's director of security research, Rik Ferguson, added that while this might mark the end of Lulzsec, it would be premature to say the same about Anonymous.
"Anonymous is a very different organisation to LulzSec and other more closely linked groups - anyone can and does act in the name of Anonymous and their activities do not require individual hacker publicity or disclosure of personally identifiable details," he said.
"The very fact that Sabu became the 'celebrity' he was, illustrates the real difference between LulzSec and Anonymous.
"I think the hackers we really need to worry about are those that trusted no-one and sought no glory in the first place."
