Austrian banker Sonja Kohn was a "criminal soul mate" of Bernard Madoff for 23 years, running an international network of banks and funds to help perpetrate the biggest fraud in financial history, a court-appointed trustee for the Madoff firm said on Friday.

Irving Picard, the lawyer recovering money for the victims of Madoff's decades-long multibillion dollar fraud, sued Kohn and the bank she founded, Bank Medici, as well as Italy's UniCredit CRID.MI and its unit, Bank Austria, and 53 other defendants.