United States Treasury
Specially Designated Nationals
The Office of Foreign Assets Control (OFAC) of the US Department of the Treasury administers and enforces economic and trade sanctions based on US foreign policy and national security goals against targeted foreign countries, terrorists, international narcotics traffickers, and those engaged in activities related to the proliferation of weapons of mass destruction.
One of the things OFAC does is to maintain a list of Specially Designated Nationals. These SDNs are individuals and organizations that—because of ties to terrorism, drug trafficking, and other bad stuff—are subject to denial entry into the United States, economic sanctions, etc. It almost goes without saying that the individuals on the SDN list are not the kind of folks we want living quietly among us.
The SDN database is a searchable list of several thousand of these menaces, as well as all their known aliases. Think you have a bad guy living next door? Just punch his name into the form below. If you get a hit, take a moment to validate your evidence against OFAC's guidelines. If you still think you have a lead on a bona-fide bad guy, call OFAC's toll-free hotline at (800) 540-6322.