BOSTON, USA: A 28-year-old college dropout pleaded guilty on Tuesday to charges that he stole tens of millions of payment card numbers by breaking into corporate computer systems.

Albert Gonzalez told a federal judge in Boston that he engineered electronic heists at companies including payment card processor Heartland Payment Systems, 7-Eleven Inc and the Hannaford chain of New England grocery stores.

Gonzalez has previously pleaded guilty to computer break-ins at retailers TJX Cos Inc, BJ's Wholesale Club Inc and Barnes & Noble.

He faces 17 to 25 years in prison when he is sentenced in March in the largest case of identity theft in U.S. history. The two judges responsible for doling out the punishment have considerable leeway in sentencing.

"You face a considerable amount of time in jail as a result of your plea," U.S. district Judge Douglas Woodlock told Gonzalez. "All aspects of your life are to be affected."

Gonzalez's attorney, Martin Weinberg, has asked for the judges to be lenient, saying his client suffers from Internet addiction, drug abuse and symptoms of a mild form of autism known as Asperger syndrome.

Gonzalez, who appeared in court wearing a beige prison uniform, told the judge that he had abused alcohol and illegal drugs for years. He mentioned marijuana, cocaine, LSD, ketamine and hallucinogenic mushrooms.

"It's one of the reasons to explain why a young man in his 20s did these things," Weinberg said.

A psychiatrist hired by Gonzalez has told the court that the hacker's criminal behavior "was consistent with the description of the Asperger's disorder." Prosecutors have petitioned the court to perform their own psychiatric evaluation of Gonzalez.

Weinberg has sought to block that request, saying it is unprecedented to conduct a psychiatric evaluation prior to sentencing. "He's admitted responsibility. He is remorseful," Weinberg said.

A U.S. federal court in Boston last week sentenced one of Gonzalez's conspirators, Stephen Watt of New York, to two years in prison for developing the software used to capture payment card data. It also ordered him to pay $171.5 million in restitution.