The board of directors plays a leading role in overseeing the ethical atmosphere of an organization. They are responsible for establishing and promoting the organization's values and ethical standards. The board sets the tone at the top and ensures that senior management implements policies and procedures that support ethical behavior throughout the organization. This oversight includes monitoring compliance with ethical standards and addressing any ethical issues that arise.
The IIA's International Professional Practices Framework (IPPF) - Practice Guide on Ethical Leadership.
COSO's Enterprise Risk Management - Integrating with Strategy and Performance.

Employing the use of data analytics tools to sort, analyze, and detect anomalies in the data best demonstrates due professional care by the internal auditor. This approach allows for efficient and effective review of large volumes of data, enabling the auditor to identify patterns and irregularities that may indicate fraudulent transactions, while also adhering to the principles of competence and due care outlined in the IIA's standards.
IIA Standards for the Professional Practice of Internal Auditing

According to The IIA's Code of Ethics, the principle of integrity emphasizes the importance of honesty and fairness in the auditor's conduct. The statement that best reflects this principle is that auditors must disclose all material facts known to them that, if not disclosed, may distort the reporting of activities under review. This aspect of integrity ensures transparency and accuracy in the presentation of audit findings, crucial for the credibility of the audit function and the trust placed in it by stakeholders.
The IIA's Code of Ethics - Integrity

Performing an annual organization-wide employee survey is a proactive role for the internal audit activity with regard to the organization's ethics program. This survey can help assess the ethical climate, identify potential ethical issues, and gather employee perceptions and feedback. The results can be used to improve the ethics program, enhance training, and ensure that ethical standards are effectively communicated and upheld throughout the organization.
The IIA's Practice Guide on Evaluating Ethics-Related Programs and Activities.
The IIA's International Professional Practices Framework (IPPF) on Assessing Organizational Ethics.

A chief audit executive might obtain the services of a fraud specialist to assist in a major fraud investigation because fraud specialists are better equipped to act as an expert witness in court. Their expertise and credentials in fraud investigations provide authoritative insight and detailed knowledge that can support legal proceedings, making them valuable resources in cases where legal actions are pursued.
The IIA's guidance on managing and investigating fraud.