Mark Felt, the mysterious "Deep Throat" source who helped Washington Post reporters Bob Woodward and Carl Bernstein crack the Watergate scandal that brought down Richard Nixon, has died, aged 95.
Mr Felt suffered from congestive heart failure but the exact cause of his death at home was not known.
The New York Times called him "the most famous anonymous source in American history".
Mr Felt, the number two official at the FBI when the Watergate case broke, kept his role in the story a secret for 30 years. Only in 2005, at 91, was his part made public in an article in Vanity Fair magazine.
For years, people had speculated and argued about the identity of "Deep Throat", whose name was derived from the title of a popular pornographic movie.
Vanity Fair scooped Woodward and Bernstein, who had promised not to reveal the name of the star source of their 1974 stories until after his death. But within a day of Felt's unveiling, Woodward wrote of his relationship with Felt.
Reporting by the Washington Post and other news outlets on the White House's involvement in the Watergate break-in and other political "dirty tricks" forced Mr Nixon's resignation from the presidency in 1974.
More than 30 officials would ultimately plead guilty or be convicted, including attorney-general John Mitchell, who served 19 months for conspiracy, obstruction of justice and perjury.
