A secretive group of cyber-pirates stole copyrighted software, games and movies in what law enforcement authorities on Wednesday termed a "massive" theft for their own pleasure, not profit.

The indictments were announced by U.S. Attorney Patrick Fitzgerald in Chicago against 19 members of the underground piracy group known as "RISCISO," led by Sean O'Toole, 26, of Perth, Australia.

Another member of the group implicated in the FBI's investigation, dubbed "Operation Jolly Roger," was Linda Waldron, 57, of Barbados. Extradition will be sought for both.

As many as 60 members of the group, many of whom work in the computer field and live across the United States, tapped into their tightly controlled computer servers loaded with stolen merchandise that would fill 23,000 compact discs and was valued at $6.5 million, prosecutors said.

Initially, the stolen software was sent to servers set up overseas.

"This was not someone illegally downloading a song," Fitzgerald said in announcing the 15-count indictment charging conspiracy to commit copyright infringement and other charges. "These were copyright violations on a massive scale."

The secretive RISCISO group — an acronym for Rise in Superior Couriering [but usually Reduced Instruction Set Chip], plus the common file format ISO — cracked expiration and encryption codes built into trial software available on the Internet, on computer games and on first-run movies intended only for reviewers and screeners, prosecutors said.

An FBI agent in charge of the probe said group members apparently acted in part out of the "thrill" of breaking the codes and to use the stolen items themselves, and did not appear to have tried to profit financially from the theft.

An informant helped the FBI crack the case.

All 19 face a charge of conspiracy to commit copyright infringement, which carries a maximum sentence of five years in prison and a $250,000 fine, plus restitution, prosecutors said.