“I’m reading more now about how suspicious they were than I ever realized at the time,” he said with a faint smile.

He did not assert that any specific bank or fund knew about or was an accomplice in his Ponzi scheme, which lasted at least 16 years and consumed about $20 billion in lost cash and almost $65 billion in paper wealth. Rather, he cited a failure to conduct normal scrutiny.

Both the interview and the e-mail correspondence were conducted as part of this reporter’s research for a coming book on the Madoff scandal, “The Wizard of Lies: Bernie Madoff and the Death of Trust,” for publication this spring by Times Books, a division of Henry Holt & Company.

In the interview and e-mails, he also claimed he had been helping the court-appointed trustee who is seeking to recover lost billions on behalf of his swindled clients. In e-mails, Mr. Madoff said repeatedly that he provided useful information to Irving H. Picard, the trustee trying to recover assets for the fraud victims. He met with Mr. Picard’s team over four days last summer, he said. The e-mails were written in December and January, but he only recently agreed that they could be made public.

In prison, Mr. Madoff’s access to the outside world is both limited and monitored. All visitors must be approved by prison authorities, who also screen his limited collect calls and his incoming and outgoing e-mails and letters, though interviews with lawyers are less restricted and can be conducted in private.

Asked about his cell, he described a room about 12 feet square with a big window looking out on the grounds; he said he had a roommate, the second since he arrived at the prison.

It was clear from the e-mails and interview here that Mr. Madoff closely followed news related to his case in December, the second anniversary of his arrest. He lashed out at what he called some of the “disgraceful” coverage of the suicide of his son Mark on Dec. 11.