The Financial Crimes Enforcement Network (FinCEN) is a US Treasury Department agency that works to protect the financial system from illegal activity:

Purpose

FinCEN's mission is to combat money laundering, terrorist financing, and other financial crimes.

Responsibilities

FinCEN's responsibilities include:

• Collecting, analyzing, and sharing financial intelligence;
• Managing data collection, processing, storage, and protection;
• Analyzing transactional reports from financial institutions;
• Sharing information with international financial intelligence units;
• Supporting law enforcement with investigations and prosecutions; and
• Issuing regulations to strengthen anti-money laundering efforts. Collaboration
  FinCEN works with international organizations and counterpart agencies in other countries.