Border Patrol Under Scrutiny for Deadly Force A pair of Mexican drug smugglers in camouflage pants, bundles of marijuana strapped to their backs, scaled a 25 foot-high fence in the middle of the night, slipped quietly into the United States and dashed into the darkness. U.S. Border Patrol agents and local police gave chase on foot - from bushes to behind homes, then back to the fence. The conflict escalated. Authorities say they were being pelted with rocks. One agent responded by aiming a gun into Mexico and firing multiple shots at the assailant, killing a 16-year-old boy whose family says was just in the wrong place at the wrong time. The Oct. 10 shooting has prompted renewed outcry over the Border Patrol's use-of-force policies and angered human rights activists and Mexican officials who believe the incident has become part of a disturbing trend along the border - gunning down rock-throwers rather than using non-lethal weapons. The Department of Homeland Security Office of Inspector General has launched a probe of the agency's policies, the first such broad look at the tactics of an organization with 18,500 agents deployed to the Southwest region alone. The Mexican government has pleaded with the U.S. to change its ways. And the U.N. High Commissioner for Human Rights has questioned the excessive use of force by Border Patrol. In this Aug. 9, 2012, photo, vehicles are parked along the border fence as pedestrians cross the street in Nogales, Mexico. The location is near the site where a U.S. Border Patrol agent being pelted with rocks opened fire toward Mexico, killing a 16-year-old boy. The shooting has prompted renewed outcry over the Border Patrol's use-of-force policies and angered human rights activists and Mexican officials who believe the incident has become part of a disturbing trend along the border _ gunning down rock-throwers rather than using non-lethal weapons. At least 16 people have been killed by agents along the Mexico border since 2010, eight in cases where federal authorities said they were being attacked with rocks, said Vicki Gaubeca, director of the ACLU's Regional Center for Border Rights in Las Cruces, N.M. The Border Patrol says sometimes lethal force is necessary: Its agents were assaulted with rocks 249 times in the 2012 fiscal year, causing injuries ranging from minor abrasions to major head contusions. It is a common occurrence along the border for rocks to be thrown from Mexico at agents in the U.S. by people trying to distract them from making arrests or merely to harass them - particularly in areas that are heavily trafficked by drug smugglers and illegal immigrants. Still, Gaubeca balks at what she and others deem the unequal "use of force to use a bullet against a rock." "There has not been a single death of a Border Patrol agent caused by a rock," she said. Why aren't they doing something to protect their agents, like giving them helmets and shields? The Border Patrol has declined to discuss its use of lethal force policy in detail, but notes agents may protect themselves and their colleagues when their lives are threatened, and rocks are considered deadly weapons. Kent Lundgren, chairman of the National Association of Former Border Patrol Officers, recalled a time in the 1970s when he was hit in the head while patrolling the border near El Paso, Texas. "It put me on my knees," Lundgren said. Had that rock caught me in the temple, it would have been lethal, I have no doubt. It is extremely rare for U.S. border authorities to face criminal charges for deaths or injuries to migrants. In April, federal prosecutors said there was insufficient evidence to pursue charges against a Border Patrol agent in the 2010 shooting death of a 15-year-old Mexican in Texas. In 2008, a case was dismissed against a Border Patrol agent facing a murder charge after two mistrials. Witnesses testified the agent shot a man without provocation but defense attorneys contended the Mexican migrant tried to hit the agent with a rock.