BOSTON - Eleven people, including a U.S. Secret Service informant, have been charged in connection with the hacking of nine major retailers and the theft and sale of more than 41 million credit- and debit-card numbers, the Justice Department announced Tuesday.

The data breach is believed to be the largest hacking and identity-theft case ever prosecuted by the Department of Justice, which said the suspects were charged with conspiracy, computer intrusion, fraud and identity theft.

Three of those charged are U.S. citizens, while the others are from places such as Estonia, Ukraine, Belarus and China.

The indictment returned Tuesday by a federal grand jury in Boston alleges that the suspects hacked into the wireless computer networks of retailers including TJX Companies, BJ's Wholesale Club, OfficeMax, Boston Market, Barnes & Noble, Sports Authority, Forever 21 and DSW and set up programs that captured card numbers, passwords and account information.

"They used sophisticated computer hacking techniques that would allow them to breach security systems and install programs that gathered enormous quantities of personal financial data, which they then allegedly either sold to others or used themselves," Attorney General Michael Mukasey said at a news conference.

He called the total dollar amount of the alleged theft "impossible to quantify at this point."

In the Boston indictment, alleged ringleader Albert (Segvec) Gonzalez of Miami was charged with computer fraud, wire fraud, access device fraud, aggravated identity theft and conspiracy. Now in custody in New York, he faces a maximum penalty of life in prison if convicted of all the charges.

Gonzalez was a U.S. Secret Service informant who helped the agency take over a website being used to transmit stolen identifiers and stolen credit card numbers, U.S. Secret Service Director Mark Sullivan said at the news conference.