Well, that and not paying a $7500 fine for money laundering. At Open Borders:

A former Mexican official arrested last month in the Rio Grande Valley after being accused of failing to pay a fine has been charged with impersonating a U.S. citizen to cross the border.

U.S. marshals arrested Edmundo Lozano Rendón, 55, in McAllen, saying he didn’t pay a $7,500 fine assessed when he was convicted of money laundering charges in 1992.

The most interesting stuff there is in the details regarding his passport.

Keep an eye on this case to see how ICE treats it.