When evidence of multiple incidents of fraud is discovered and there are insufficient controls in place, the internal auditor's most appropriate next step is to discuss the situation with the engagement supervisor to determine whether fraud investigation experts are needed. This step ensures that specialized expertise is considered and engaged if necessary to properly investigate the matter and to determine the appropriate response, including the potential involvement of law enforcement.

International Standards for the Professional Practice of Internal Auditing on responding to findings and incidents of fraud; guidance on fraud investigation.