The auditor of BLMIS, David Friehling, failed to uphold the fundamental principles governing an audit by not exercising due care or maintaining professional skepticism. He disregarded his responsibility to independently verify BLMIS's assets, review revenue sources, examine bank accounts, verify liabilities, or confirm the purchase and custody of securities. Additionally, Friehling and his relatives had personal accounts with BLMIS, compromising his independence. In summary, Friehling showed a lack of intent to properly audit BLMIS and gather sufficient evidence, violating several key audit principles.