A former American senator who survived seven and a half years as a prisoner of war in North Vietnam and alerted the U.S. military to conditions there when he blinked the word torture in Morse Code during a television interview, has died due to heart problems. Jeremiah Denton was 89. Denton served a single term in the Senate. His iron will that served him in such good stead in captivity, gave rise to criticism that he was too rigid as a politician .