Afghan police stand guard outside police headquarters in Kabul, Afghanistan, where an American adviser was killed, authorities said, by an Afghan policewoman on Monday, Dec. 24, 2012. (AP Photo/Musadeq Sadeq)

Photo by: Musadeq Sadeq

Afghan police stand guard outside police headquarters in Kabul, Afghanistan, where an American adviser was killed, authorities said, by an Afghan policewoman on Monday, Dec. 24, 2012. (AP Photo/Musadeq Sadeq)