Bernard L. Madoff said he never thought the collapse of his Ponzi scheme would cause the sort of destruction that has befallen his family. In his first interview for publication since his arrest in December 2008, Mr. Madoff — looking noticeably thinner and rumpled in khaki prison garb — maintained that family members knew nothing about his crimes. But during a private two-hour interview in a visitor room here on Tuesday, and in earlier e-mail exchanges, he asserted that unidentified banks and hedge funds were somehow “complicit” in his elaborate fraud, an about-face from earlier claims that he was the...