Question About the Role of Inspectors General in National Security

I am trying to collect major examples of the various roles that inspectors general play in national security.  Below I have broken down their roles into three categories, and listed examples of each.  (I have excluded and am not interested in auditing functions.)  I would be grateful if informed readers could help me identify more categories and provide more examples in each category.  If you have thoughts, please email me at goldsmith.lawfare@gmail.com.  I will publish on lawfareblog what, if anything, I learn (unless someone who sends me information asks me not to).  Thanks. Internal Investigators

• CIA Inspector General: reports on CIA detention and interrogation program, Peru shootdown program, and CIA accountability for 9/11.

• DOJ Inspector General: reports on Immigration detainees after 9/11, FBI use of National Security Letters, FBI involvement in detainee interrogations, Terrorist screening center, FBI foreign language translation program, domestic advocacy groups, FBI use of exigent letters.

Information-gatherers for Congress

• Terrorist Surveillance Program (with other IGs)
• Many information tasks to various IGs in the 2010 Intelligence Authorization Law
• Large information-gathering and analysis role for various IGs in 2008 FISA Amendments

Credibility-enhancers for the Executive

• Obama DOJ internal State Secrets policy says that DOJ will refer credible allegations of government wrongdoing that are shielded by state secrets privilege to IG of appropriate department.