On Oct. 10, 2012, one or more Border Patrol agents shot an unarmed Mexican teenager 10 times in the back and head, firing through the border fence from Arizona into Nogales, Mexico. Agents said Jose Antonio Elena Rodriguez had thrown rocks at them. But their version of events didn't square with the facts. As Arizona Republic reporters dug further into that killing and into 41 other cases of deadly force by on-duty Border Patrol agents, they found that agents who use deadly force face few if any public repercussions, even when the cases appear dubious. They found that agents who kill are protected by a culture of secrecy at Customs and Border Protection. The country's largest law-enforcement body, CBP also is among the least transparent - in fact, its policies fly in the face of best practices recommended by national police organizations. The investigation found previously unreported deaths at the hands of agents. It found that hundreds of Border Patrol agents didn't use deadly force, despite facing the same circumstances as the agents who killed. In addition, it examined why border deaths don't spark outrage and how the Border Patrol is increasingly backing up local police and conducting local police duties.