From the Document: "As directed by Congress, we conduct annual unannounced inspections of U.S. Immigration and Customs Enforcement (ICE) detention facilities to ensure compliance with detention standards. In 2019, we inspected four detention facilities to evaluate their compliance with ICE detention standards."
Department of Homeland Security, Office of Inspector General, Report No. OIG-20-45
U.S. Department of Homeland Security. Office of Inspector General: https://www.oig.dhs.gov/