A man suspected of being the serial bank robber dubbed the "Mad Hatter" will plead guilty to several bank robbery counts on Wednesday, an official with knowledge of the case said Monday.

James G. Madison will acknowledge he was the hat-wearing man who robbed 18 banks in a spree that began in September and ended with his arrest July 23, according to the official.

A second official with knowledge of the case also said Monday that Madison was expected to plead guilty on Wednesday. Both officials spoke only on condition of anonymity because they weren't authorized to discuss the case publicly.

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Madison's public defender, Donald J. McCauley, did not immediately return a message on Monday seeking comment.

Madison, 50, of Maplewood, was indicted on a single count of bank robbery following his arrest. The charge carries up to 20 years in prison.

The balding 50-year-old machinist has been held without bail since his arrest, which came a day after authorities said he robbed a Bank of America branch in Union Township.

That heist proved to the Mad Hatter's undoing. According to police, a bank employee wrote down the license number of a car used in the robbery. The vehicle was traced to a woman who lives with Madison. The woman told investigators she had loaned him her vehicle, authorities said.

The robbery followed the pattern of other robberies attributed to the elusive Mad Hatter: a hat-wearing man who quietly passed a note to a teller demanding money. The FBI has said the notes were similar.

Prosecutor Shana W. Chen did not return a message seeking comment. Michael Drewniak, a spokesman for the federal prosecutor's office, declined to comment. The FBI agent in charge of the Newark office, Weysan Dun, on Monday would say only that the investigation was continuing.

Madison spent nearly two decades in prison for murdering his girlfriend in 1986. Authorities said he struck Terry Wells with a lamp during a fight. Her body was later found in a suitcase fished out of the Passaic River.

Madison was paroled in 2005 after serving 18 years of a 40-year sentence. Authorities said he lived in a halfway house for part of 2006 and moved out a few months before the string of robberies began last fall.

Days after his arrest, Madison granted a jailhouse interview to The Star Ledger of Newark and denied all involvement in the heists.

"I don't rob people," Madison told the newspaper. "I don't wear hats."

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