Airmen of the 633d Security Forces Squadron present Argo, 633 SFS Military Working Dog, his certificate of retirement at Langley Air Force Base, Va., May 20, 2011. The retirement ceremony was held in conjunction with National Police Week, an annual event to pay recognition to military and civilian law enforcement officers who lost their lives in the line of duty. (U.S. Air Force photo by Airman 1st Class Camilla Griffin)(RELEASED)