From the Summary: "Federal law establishes a variety of inspectors general (IGs), each of whom is generally tasked with detecting waste, fraud, and abuse through independent and objective investigations, audits, and reviews of the agency or program for which they are responsible. In 2020, the level of independence that IGs possess received significant public and congressional attention after President Donald Trump removed or replaced two permanent and two acting IGs in the span of two months. Although IGs are independent and objective units, they are not completely insulated from executive branch influence. Under the Inspector General Act of 1978 (IG Act), IGs are appointed, supervised, and removed by either the President or agency leadership."
CRS Report for Congress, R46762
Congressional Research Service: https://crsreports.congress.gov/