The U.S. Department of State is the foreign affairs agency of the United States government. It is administered by the Secretary of State.
The U.S. Department of State has developed a "National Strategy Against High Level Corruption: Coordinating International Efforts to Combat Kleptacracy". This is basically a brief policy statement establishing the United States commitment to fight corruption. This National Strategy can be found at http://www.state.gov/documents/organization/70333.pdf.
The Department of State participates in the negotiation of various treaties and multilateral conventions. The department also has an investigative arm, the Bureau of Diplomatic Security (DS). The special agents within DS participate in corruption, money laundering and terrorism investigations. Each U.S. embassy will have DS special agent designated as the Regional Security Officer (RSO). The RSO is an excellent contact in foreign countries through which informal information can be requested.