Finding auditors to investigate different aspects of the payment crisis in the National Spot Exchange Ltd (NSEL) has become a challenge for the investigative agencies and regulators. Two of the Big Four audit firms were involved in the audit work of the group firms that own NSEL. Another has been an empanelled system auditor in one of the associated exchanges. The fourth one's name has been closely associated with an earlier corporate scandal. Regulators are worried about giving the firm that has already been hired for a couple of forensic audits more work for fear of raising allegations of favouritism. But there are serious doubts if other auditors down the ranks have the bandwidth to perform detailed audits.