633d Security Forces Airmen present Argo, 633d SFS Military Working Dog, his retirement certificate during National Police Week at Langley Air Force Base, Va., May 20, 2011. The National Police Week occurs each year and pays special recognition to those law enforcement officers, civilian and military, who have lost their lives in the line of duty. (U.S. Air Force photo by Airman 1st Class Camilla Griffin)(RELEASED)