Zenon, Inc., A Fortune 500 company, has been experiencing some slow performance results the last few years. Industry analysis have been negative reports and the company's stock price has been declining. In the course of the audit of Zenon, you find that some accounting entries may have been altered and this could be material to the financial statements. You know the company history and you suspect management fraud. As the auditor what should concern you about the Zenon audit engagement? What steps should you take in response to the accounting entries and your concern about management fraud?