From the Document: "Established by the Homeland Security Act of 2002, the Office of the Citizenship and Immigration Services Ombudsman (Ombudsman) is an independent, impartial, and confidential office within the Department of Homeland Security (DHS). The Ombudsman reports directly to the Deputy Secretary of DHS and is independent of U.S. Citizenship and Immigration Services (USCIS). [...] Ombudsman's mission is limited to issues dealing with immigration benefits, but in certain circumstances the Office can assist with cross-agency issues."
U.S. Department of Homeland Security: http://www.dhs.gov/