Illegal immigrants caught by US Border Patrol Black Hawk helicopters trying to make their way north from Mexican border near Three Points, Arizona

U.S. Border Patrol officials are facing an immigration loophole dubbed OTM, or Other Than Mexicans, that has allowed thousands of people from Central and South America to cross illegally into the United States.

Unlike Mexicans who are deported as soon as they are caught, undocumented non-Mexicans surrender to Border Patrol agents immediately knowing they will be given a "notice to appear" at an immigration hearing weeks later. Most OTM illegals never show up for that hearing.

Brazilians are now the largest category of Other Than Mexicans who cross illegally into the United States. In the first half of 2005, more than 12,000 undocumented Brazilians have been caught and released by the U.S. Border Patrol, exceeding the total count from 2004.

Border Patrol statistics show 39,000 non-Mexican crossers were caught in all of 2003. That number has already reached 85,000 this year.