How a big US bank laundered billions from Mexico's murderous drug gangs

On 10 April 2006, a DC-9 jet landed in the port city of Ciudad del Carmen, on the Gulf of Mexico, as the sun was setting. Mexican soldiers, waiting to intercept it, found 128 cases packed with 5.7 tons of cocaine, valued at $100m. But something else – more important and far-reaching – was discovered in the paper trail behind the purchase of the plane by the Sinaloa narco-trafficking cartel.

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. Of special significance was that the period concerned began in 2004, which coincided with the first escalation of violence along the US-Mexico border that ignited the current drugs war.

Criminal proceedings were brought against Wachovia, though not against any individual, but the case never came to court. In March 2010, Wachovia settled the biggest action brought under the US bank secrecy act, through the US district court in Miami. Now that the year's "deferred prosecution" has expired, the bank is in effect in the clear. It paid federal authorities $110m in forfeiture, for allowing transactions later proved to be connected to drug smuggling, and incurred a $50m fine for failing to monitor cash used to ship 22 tons of cocaine.