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 charged 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 Unicredit bank, Bank Austria and 53 other defendants for $19.6 billion.