South Asians often use an informal network of brokers, called a "hawala," to transfer money over long distances when it is too inconvenient or dangerous to send cash by courier.
The centuries-old system is used to move billions of dollars in and out of countries like Pakistan, Afghanistan and Somalia - often to the chagrin of US law enforcement.
A law enforcement official told The Associated Press that terror suspect Faisal Shahzad is believed to have tapped into such a network to help fund a plot to detonate a car bomb in Times Square. The official spoke on condition of anonymity because the investigation is ongoing.
Authorities say three men helped get money to Shahzad although they might not have known how the money was going to be used.