A man said to be a member of Bernard Madoff’s “inner circle” has agreed to plead guilty to helping the swindler cook the books, federal prosecutors said in a letter made public last week. Eric Lipkin, a second-generation Madoff employee who worked at his secretive investment advisory business for 16 years, is expected to appear in court today to admit his role in the epic fraud, prosecutors said in a letter to Southern District Judge Laura Taylor Swain.

The letter said Mr. Lipkin would plead guilty to a six-count criminal complaint that will be submitted to the court today and will include charges of conspiracy, bank fraud and falsifying various financial records. He is entering the plea as part of a cooperation agreement with prosecutors, but the letter did not specify what sort of assistance he has been asked to provide. Mr. Lipkin’s lawyer, James Filan, declined to comment.