From this:

[Wachovia Bank]... made a habit of helping move money for Mexican drug smugglers. Wells Fargo & Co., which bought Wachovia in 2008, has admitted in court that its unit failed to monitor and report suspected money laundering by narcotics traffickers... The admission came in an agreement that Charlotte, North Carolina-based Wachovia struck with federal prosecutors in March... Wachovia admitted it didn’t do enough to spot illicit funds in handling $378.4 billion for Mexican-currency-exchange houses from 2004 to 2007. That’s the largest violation of the Bank Secrecy Act, an anti-money-laundering law, in U.S. history -- a sum equal to one-third of Mexico’s current gross domestic product...

[Wachovia isn't alone...] Miami-based American Express Bank International paid fines in both 1994 and 2007 after admitting it had failed to spot and report drug dealers laundering money through its accounts. Drug traffickers used accounts at Bank of America in Oklahoma City to buy three planes that carried 10 tons of cocaine, according to Mexican court filings...

[...BofA and another bank, HSBC, haven't been charged...]

...Large banks are protected from indictments by a variant of the too-big-to-fail theory...

Also see immigration banks for domestic examples of banks trying to profit from money that was earned illegally, as well as those like Arnold Schwarzenegger who want to help them.