Early next year, a Chinese businessman named Gan Xianbing will be sentenced in a Chicago courtroom for laundering just over $530,000 in Mexican cartel drug money.

Gan, 50, was convicted in February of money laundering and operating an unlicensed money-transfer business that whisked cartel cash from U.S. drug sales offshore. Gan has maintained his innocence; his lawyers say he was entrapped by U.S. authorities. The trial garnered few headlines and little of the public fascination reserved for kingpins of powerful narcotics syndicates that U.S. federal prosecutors said Gan served.

Still, U.S. law enforcement officials said that Chinese "money brokers" such as Gan represent one of the most worrisome new threats in their war on drugs. They say small cells of Chinese criminals have upended the way narcotics cash is laundered and are displacing the Mexican and Colombian money men that have long dominated the trade.