WASHINGTON (AP) — Frank Mankiewicz, the press secretary who went before television cameras to announce the death of Sen. Robert F. Kennedy and later served as political director for presidential candidate George McGovern, died Thursday. He was 90. Mankiewicz died of a heart attack at George Washington University Hospital, said a family friend, journalist Adam Clymer. Mankiewicz was a longtime Democratic political operative as well as a lawyer, journalist and author.