Border Patrol Agent's Killer: Friendly Fire, Sources Say

Border Patrol agent Nicholas Ivie was apparently not shot by Mexican drug runners after all. Federal and state officials tell NBC that another agent at the scene accidentally killed Ivie. Investigators based their conclusion on ballistics analysis, the lack of proof that other gunmen were there, and other evidence, the sources say. A formal statement from officials is expected soon.

Mexican authorities have already arrested two people initially suspected of being connected to the shooting, nabbing them during a military operation in Agua Prieta, which is just a few miles from where Ivie was shot. (More Border Patrol stories.)