3 / 9
In this undated photo provided by the Ivie family, Border Patrol Agent Nicholas Ivie is seen. Ivie, a 30-year-old father of two, was shot and killed in the sparsely populated desert in southeastern Arizona early Tuesday, Oct. 2, 2012. (AP Photo/Ivie Family, Cole Kynaston)

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)