Arizona's Monument Valley is known for its red sandstone buttes and spires, but now it's notorious for something else: crime. The Navajo Nation is one of the most violent reservations in the country. According to FBI reports, over the past five years, more rapes were reported on the Navajo Nation than in San Diego, Detroit or Denver, among other cities.

The U.S. attorney's office tries to take on the most violent crimes, but it often lacks enough evidence to prosecute. And because of antiquated tribal codes, Navajo courts can only order someone to serve one year in jail.

Tuba City, Ariz., jail supervisor Robbin Preston shows off his new state-of-the-art building on the Navajo Nation, about an hour north of Flagstaff.

"This is our sally port," he says, "so whenever police officers are bringing inmates in, they'll notify our central at the gate, and then we'll bring them through here."

Preston says that up until recently, Tuba City had an Old West-style jail with just 10 beds in a building that was falling apart. The jail was so full, in fact, it could only hold inmates for eight hours. The recidivism rate was so high, Preston couldn't keep track of it.