Historically, banking regulators primarily handled money-laundering investigations, but DOJ has recently launched several of its own criminal cases under the Bank Secrecy Act (BSA). The BSA requires financial institutions and their employees to combat money laundering. Michael Dawson, managing director of Promontory Financial Group, noted "the involvement of the Department of Justice in sanctions and enforcement actions is much greater now than it was five years ago, and the size of the fines has increased by a factor of 10 or more."
According to the article, in 2010 DOJ fined Wachovia $110 million for violating the BSA by failing to stop millions in Colombian and Mexican drug money from being laundered through its bank accounts.
The U.S. Treasury's Office of Foreign Assets Control (OFAC) has also increased money laundering fines. In 2011, OFAC fined 21 companies a total of $91 million. Through October 2012, OFAC fined 11 companies a total of $623 million.
Some speculate that the agencies' increased money laundering focus is due to congressional criticism that they were previously slow to act. Others posit that resources were reallocated to deal with the financial crisis for the past few years.