One of the most prolific computer hackers in U.S. history pleaded guilty today in federal court in Pittsburgh to stealing 1.8 million credit card numbers in a fraud case that prosecutors said cost banks $86.4 million.

Max Vision, formerly known as Max Butler, of San Francisco, admitted that he used high-level encryption programs to disguise his hacking into various financial institutions. He also hacked into other hackers' computers and stole their information.

"I am guilty," he told Senior U.S. District Judge Maurice Cohill Jr.

Mr. Vision, who called himself "Iceman," "Digits" and other nicknames, was the target of a 16-month investigation by agents from the U.S. Secret Service, who used two confidential informants from Western Pennsylvania to catch him.

His partner, Christopher Aragon of Los Angeles, would have testified against him had he gone to trial. Mr. Aragon is being prosecuted by the district attorney's office in Orange County, Calif.