Arlen Specter was a United States senator from Pennsylvania from 1980 to 2011. A graduate of the University of Pennsylvania (1951), he served in the Air Force during the Korean War and graduated from Yale Law School in 1956. As a hotshot assistant district attorney in Philadelphia, Arlen Specter was appointed assistant counsel to the Warren Commission's investigation of the 1963 assassination of President John F. Kennedy. Specter made a name for himself as an advocate of the "single bullet theory," the notion that one bullet from Lee Harvey Oswald caused non-fatal wounds to the president and Texas governor John Connally. (The fatal shot to Kennedy was from another bullet fired by Oswald.) Originally a Democrat, Arlen Specter became a Republican to run for Philadelphia District Attorney in 1965. He served in that post until losing a re-election bid in 1973, but he didn't stay out of politics for long. He ran unsuccessfully for the U.S. Senate (1976) and the Pennsylvania governorship (1978) before being elected to the Senate in 1980. During his time in the Senate, Specter was on the national stage often, most notably as an aggressive questioner of Anita Hill during the 1991 confirmation hearings of Supreme Court justice Clarence Thomas, and for breaking with most Republicans in his public disapproval of the 1998 impeachment of President Bill Clinton. Arlen Specter made the news again in April of 2009 when he announced he was leaving the party to become a Democrat. He ran for re-election in 2010, but lost in the Democratic primary to Joe Sestak, who lost the general election in November to Republican Pat Toomey. In later years he battled cancer and heart trouble, and he died of complications related to non-Hodgkins lymphoma on 14 October 2012.