“During a 22-month investigation by agents from the US Drug Enforcement Administration, the Internal Revenue Service and others, it emerged that the cocaine smugglers had bought the plane with money they had laundered through one of the biggest banks in the United States: Wachovia, now part of the giant Wells Fargo.

The authorities uncovered billions of dollars in wire transfers, traveller’s cheques and cash shipments through Mexican exchanges into Wachovia accounts. Wachovia was put under immediate investigation for failing to maintain an effective anti-money laundering programme.”

http://www.guardian.co.uk/world/2011/apr/03/us-bank-mexico-drug-gangs