A lot of it passes through big banks:

Some officials warn that mafias such as the Sinaloa operation have capitalised on the global financial crisis in ways we have yet fully to understand. "The illiquidity associated with the banking crisis, the reluctance of banks to lend money to one another . . . offered a golden opportunity to criminal institutions," Antonio Maria Costa, the former executive director of the United Nations Office on Drugs and Crime, said in April. "The penetration of the financial sector by criminal money has been so widespread that it would probably be more correct to say that it was not the mafia trying to penetrate the banking system, but it was the banking sector which was actively looking for capital – including criminal money . . ."