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Border patrol

U.S. Customs and Border Protection officers and other law enforcement drive the roads near where U.S. Border Patrol agent Nicholas Ivie was shot and killed, and one other was shot and injured, Tuesday, Oct. 2, 2012, in Bisbee, Ariz. (AP Photo/Ross D. Franklin)

Border Patrol agent killing

The head of the U.S. Border Patrol agents'

union says the agent killed last week in a shooting in southern Arizona

apparently opened fire on two colleagues thinking they were armed

smugglers and was killed when they returned fire. (Oct. 8)