Chinese brokers are helping Mexican cartels launder drug money

The wealthy in China want to illegally transfer their money out of the country, so money brokers in America set up to help them avoid detection. Meanwhile, drug cartels have the hard cash the Chinese would like to possess in America, and can't transfer the money to Mexico for fear of it being captured by authorities. In a long article about the drug trade, Reuters explains how the transactions work: 

Lim testified at Gan’s trial that she had two jobs. The first was collecting drug money in U.S. cities such as Chicago and New York from cartel contacts, typically anywhere from $150,000 to $1 million at a time. She would wait in a public place, armed with a burner phone, a code name and the serial number of an authentic $1 bill. Mexican cartels would pass on her details to their dealer contacts, who would call Lim’s burner phone and use the code name to identify themselves. At the rendezvous point, Lim would give them the $1 bill with the corresponding serial number as a “receipt” to verify the handoff had taken place, Lim said at trial.

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Lim would [then go to a broker] with, say, $150,000 in cartel cash. With the businessperson observing, she would open a currency converter app on her smartphone to obtain the exchange rate between the U.S. dollar and the Chinese yuan. She would also hand over the details of a bank account in China given to her by Gan. In what’s known as a “mirror transaction,” the Chinese businessperson would take possession of the $150,000 in U.S. currency while simultaneously transferring the equivalent in Chinese yuan from their own account in China to the bank account number provided by Gan.

The result was that a foreign transfer of funds had been made without involving a U.S financial institution

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To get the money from China to Mexico, Gan performed the same sort of mirror transactions, only this time with the help of Chinese businesses who had access to pesos in Mexico.