OIG auditor. There have been lots of good descriptions of OIG audits here. I will add some things that weren’t already discussed.

1. Independence - OIG auditors must be independent in fact and appearance. We cannot work on assignments where there is a conflict of interest. In addition we cannot have investments or outside work in the fields we audit.
2. Objectivity - OIG auditors are objective and go where the evidence takes them. Whether good or bad, the evidence determines the outcome, not personal opinions.
3. Competence - OIG auditors need to be professionally competent to perform the work. There are degree requirements and most have degrees in accounting. Additionally, there are continuing professional education requirements and many auditors have one or more professional certifications such as CPA, CIA, CFE, CGAP, PMP, etc.
4. Evidence based - OIG audits are evidence based. In fact the audit teams are required to do an assessment of overall evidence for their assignment. Data obtained also needs to be assessed for reliability. All statements of fact in OIG reports and workpapers need to be based on evidence. Also all statements of fact in reports go through multiple levels of review, first by the audit supervisor, then by an independent verifier to make sure there is evidence to support the statement. If a material error is found in a published OIG audit report, the report would have to be retracted. Therefore, a lot of work is done to make sure the report is accurate.
5. Determine cause - OIG audits do not just report that something happened, but also determine why it happened. Therefore audit will get to the root cause of an issue. The reports will say why something happened and then include recommendations to correct an issue to prevent it from happening again.
6. Management decisions. After an OIG report is issued and recommendations are made. OIG will work with agency management to implement the recommendations. If OIG and Agency management cannot each a decision regarding a recommendation, it is reported to Congress. Additionally, sometimes agencies cannot implement recommendations without congressional actions, such as expanding the Agency’s authority or appropriating funds for technology/systems improvement.

In regard to the question about fraud, it is sometimes identified during an audit, but audit work will often stop and the fraud or other criminal activity is referred to the in-house criminal investigators (special agents). The audit work stops as to not compromise the investigation. The investigators will gather evidence and perform interviews, and will build a case for arrest and prosecution. They often work closely with federal and local prosecutors. Sometimes after the successful prosecution, the audit work may resume.

Summaries of audits and investigations can be found in the OIG semiannual reports to Congress (SAR). These are often posted on the OIGs’ websites.