Acknowledging that many Mexicans sending money home are illegal immigrants, the Federal Reserve's brochure [PDF] poses the following frequently asked question: "If I return to Mexico or am deported, will I lose the money in my bank account?" The answer: "No. The money still belongs to you and can be easily accessed at an ATM in Mexico using your debit card."

[U.S. Banks Woo Migrants, Legal Or Otherwise By MIRIAM JORDAN, Wall Street Journal, October 11, 2006]

Actually, the Federal Government could grab these bank accounts by a process known as "asset forfeiture," which they're entirely too eager to use on Americans, but they won't.