A younger brother of President John F. Kennedy, who served as attorney general during his brother's presidency and was his brother's closest adviser. Robert Kennedy, also known as Bobby, was a champion of the civil rights movement and a foe of organized crime. He was elected to the Senate after John Kennedy's assassination. In 1968, while running for the presidential nomination of the Democratic party, he was assassinated by Sirhan Sirhan, a Palestinian, evidently because of Kennedy's position favoring Israel. (See Arab-Israeli conflict.)