During the design evaluation phase of an audit, the internal auditor's primary role is to assess whether the controls in place are appropriately designed to mitigate risks. This includes identifying key controls such as those over segregation of duties, which is a fundamental control to prevent fraud and errors by ensuring that no single individual has control over all aspects of a transaction.

IIA References:

IIA Standard 2201: Planning Considerations highlights the importance of evaluating the adequacy of controls during the design phase. Identifying controls over segregation of duties is a critical step in this process as it ensures that the design is robust and capable of mitigating risks.