Updated

Federal prosecutors expect the former chief financial officer for disgraced financier Bernard Madoff to plead guilty Tuesday to criminal charges.

Frank DiPascali, long rumored to be cooperating with authorities, agreed to enter the plea in federal court in Manhattan, prosecutors said Friday in a letter to a judge. The charges were not specified.

A phone call to DiPascali's attorney, Marc Mukasey, was referred to a law firm spokeswoman who declined to comment.

Earlier Friday, prosecutors filed a one-page notification with the court that they would charge DiPascali. Such a filing usually means that there's a plea deal and that the defendant is cooperating.

Madoff, 71, pleaded guilty earlier this year to charges that his secretive investment advisory business was a multibillion-dollar Ponzi scheme run at least since the early 1990s. The fraud demolished the life savings of thousands of people, wrecked charities and shook confidence in the U.S. financial system. The former Nasdaq chairman was sentenced in June to 150 years in prison.

Customers have described DiPascali, 52, as their main contact with the firm. He was the person whom they spoke with if they had questions about their accounts or wanted to add or withdraw money.

He also has a long history with Madoff: Both come from the same part of Queens. His first job was as Madoff's assistant. He went on to hold titles in the 1980s that included director of research and director of options trading. He became the firm's chief financial officer in 1996 — a post he held until the firm's collapse.

Madoff has insisted that he acted alone, and only one other person — his accountant — has been charged during the seven-month investigation. But Madoff's brother and sons, who ran a trading operation under the same roof, large investors and other insiders have come under intense scrutiny, and the FBI has said it expects more arrests before it concludes the probe.

Bradly Simon, a former federal prosecutor now in criminal defense, said it's likely DiPascali has been giving investigators inside information from the start on other potential defendants.

After Madoff's arrest late last year, DiPascali "suddenly dropped out of sight," Simon said. "It's obvious that they got to him early." The probable plea deal, he added, signals "more indictments are coming, and probably quite soon."