Former Alabama Sen. Jeremiah Denton, who survived 7 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. He was 89.

Denton's grandson, Edward Denton, says he died about 8 a.m. Friday at a hospice facility surrounded by family. Edward Denton says his grandfather had been in declining health for the past year and died from heart problems.

Denton, a Republican who served a single term in the U.S. Senate, was a strong advocate of conservative causes and backer of the Reagan administration. But the iron will that served him in such good stead in captivity gave rise to criticism that he was too rigid as a politician.