The evolving anti-laundering campaign could change the tone of the Mexican government's battle by striking at the heart of the cartels' financial empire, analysts say.
For example, Mexican traffickers are taking advantage of blind spots in monitoring the nearly $400 billion of legal commerce between the two countries. The so-called trade-based laundering allows crime groups to disguise millions of dollars in tainted funds as ordinary merchandise — say, onions or precious metals, as they are trucked across the border.
In one case, the merchandise of choice was tons of polypropylene pellets used for making plastic. Exports of the product from the United States to Mexico appeared legitimate, but law enforcement officials say that by declaring a slightly inflated value, traders were able to hide an average of more than $1 million a month, until suspicious banks shut down the operation.
There is also stubborn resistance among those who profit from their role as middlemen for big transactions.
One such group is notaries, who in Mexico have a function much like attorneys in the U.S. They handle nearly all real estate transactions and have battled a proposal that would require them to report how each purchase was paid for. Notaries say launderers would probably respond by skipping the paperwork altogether when buying cars and houses, only adding to the black-market economy.