LOS ANGELES: A San Francisco attorney who interviewed imprisoned swindler Bernard Madoff in a federal prison this week said on Wednesday (local time) he plans to amend a lawsuit to include possibly several fund managers who funneled investor money to Madoff's $65 billion Ponzi scheme.

Joseph Cotchett obtained the lengthy interview with Madoff, 71, after suing the former NASDAQ commissioner's wife, Ruth, his sons and brother, along with other parties, on behalf of duped investors in Wall Street's biggest investment fraud.

"We had been negotiating with his lawyers and his wife's lawyers for the past two months," Cotchett told Reuters. "We said if Bernie would sit down with us, we would give great consideration to letting Ruth out" of the lawsuit.