It's hard to bribe a foreign official without someone laundering the money. That's why money-laundering charges are part of most FCPA cases. Each shot-show defendant, for example, was charged with conspiracy to launder money. And it's why the DOJ uses the same law against corrupt foreign officials, as in the recent Haiti telco case. (The FCPA doesn't reach bribe takers, only bribe payers.)
The U.S. anti-money laundering law is 18 U.S.C. §1956. It packs a wallop -- a fine of a half million dollars or more, and up to 20 years in prison. (Jail terms for FCPA anti-bribery violations are five years maximum.)
What's a money-laundering offense? Knowingly using money that comes from an illegal activity; trying to conceal or disguise the nature, location, source, ownership, or control of the proceeds of unlawful activity; or trying to avoid reporting a transaction that has to be reported under state or federal law.
Foreigners are subject to the U.S. anti-money laundering law if any part of their transaction happens in the U.S., if they use property in which the U.S. has an interest (through a judgment, lien, or court order), or if they maintain a bank account at a financial institution in the U.S.
Just as bribery usually involves money laundering, money laundering usually involves tax evasion. Again in the Haiti telco case, it was the IRS's Miami field office that investigated Robert Antoine, the former director of international affairs for Haiti telco, who lived in both Miami and Haiti. He pleaded guilty last week to a money-laundering conspiracy (same statute; same potential penalties).
Evidence of money laundering often leads to discovery of other crimes. On its extensive AML website, the University of Exeter says:
Although money laundering is a threat to the good functioning of a financial system, it can also be the Achilles heel of criminal activity. In law enforcement investigations of organised criminal activity, it is frequently the connections made through financial transaction records that allow hidden assets to be located and that establish the identity of the criminals and the criminal organisation involved.
The DOJ hasn't said how often it finds FCPA offenses through money-laundering investigations.