In many ways, however, Mr. Madoff seemed unchanged. He spoke with great intensity and fluency about his dealings with various banks and hedge funds, pointing to their “willful blindness” and their failure to examine discrepancies between his regulatory filings and other information available to them.

“They had to know,” Mr. Madoff said. “But the attitude was sort of, ‘If you’re doing something wrong, we don’t want to know.’ ”