His whispered words helped topple a president. But for three decades, Mark Felt remained in the shadows. But all the time he was the unknown answer to the nation's most enduring political mystery: Who was "Deep Throat?"
Felt was second-in-command at the FBI in the early 70's, when the press began asking questions about the Watergate break in.
Felt's clandestine meetings with Washington Post reporter Bob Woodward were immortalized in the movie "All the President's Men."
Felt traded answers for anonymity - and repeatedly denied being the secret source behind the revelations that ultimately brought down President Richard Nixon.
On "Face the Nation" on Aug. 29, 1976, Felt said, "No, no, I am not Deep Throat."
But, that denial also offered a curious clue. Felt said: "I think whoever helped Woodward helped the country."
In 2005, Felt, in poor health with a fading memory, revealed his role.
Woodward, who protected Deep Throat's identity until that confession, today praised Felt's courage.
"In a sense, every bone in his body told him play by the rules. But he realized that everyone else was breaking the rules, and so he was willing to guide us and talk," Woodward said.
In his memoirs, Felt said he did the right thing.
"The bottom line is that we did get the whole truth out, and isn't that what the FBI is supposed to do?" Felt wrote.
Mark Felt died at his California home. He was 95.