Native American "Shadow Wolves" Track Smugglers and Immigrants Through Desert

TOHONO O'ODHAM NATION, AZ - JANUARY 18: U.S. Immigration and Customs Enforcement tactical officer Kevin Carlos watches as a fellow officer drives off a confiscated ATV seized with some 500 lbs. of marijuana on January 18, 2011 in the Tohono O'odham Nation, Arizona. Carlos is a member of the Shadow Wolves, the only Native American unit of the U.S. Immigration and Customs Enforcement agency. The ICE unit tracks and interdicts drug smugglers and illegal immigrants crossing into the Indian reservation along a 72-mile stretch of the U.S.-Mexico border. The reservation is a key crossing point for narcotics entering the United States. (Photo by John Moore/Getty Images)