In the United States, an immigration officer works for either the Citizenship and Immigration Services (USCIS) department or the Immigration and Customs Enforcement (ICE) department of the federal government. If you work for the USCIS, you typically have a Fraud Detection and National Security (FDNS) designation, and your duties are to monitor for and investigate different types of fraud related to immigration or identification benefits or fraud on immigration applications. ICE officers, on the other hand, are law enforcement officers whose responsibilities are to police the border and investigate and detain undocumented immigrants.