WATERGATE whistle-blower Deep Throat played a central role in one of the biggest White House scandals ever, helping bring down a president and inspire a political mystery so famous his nickname earned an entry in Webster's.
Thirty years later, the source is secret no more.
At the age of 91, after decades of hiding his role as The Washington Post's tipster from politicians, the public and even his family, former FBI official Mark Felt told his secret to a lawyer his family had consulted on whether Felt should come forward.
The attorney, John O'Connor, then wrote a Vanity Fair magazine article revealing Felt's disclosure, and within hours of the story's release on Tuesday, Felt's family and the Post confirmed it.
"It's the last secret" of the story, said Ben Bradlee, the paper's top editor at the time the riveting political drama played out three decades ago.
Felt lives in Santa Rosa, California, and is said to be in poor mental and physical health because of a stroke, and has not directly spoken to the media.
Born in Twin Falls, Idaho, in 1913, he graduated from the University of Idaho, went to George Washington University Law School and joined the FBI in 1942.
For many, Felt's admission answers one of the biggest questions in American politics and journalism: who was the source so fearful he'd be found out by the Richard Nixon White House that he insisted on secret signals rather than phone calls to arrange meetings with the Post reporters?
"A good secret deserves a decent burial and this one is going to get a state funeral," said Leonard Garment,
acting special counsel to President Nixon after the Watergate story broke and author of the book In Search of Deep Throat.
Felt "had the credentials, he had the knowledge, he had a series of
motives, he probably was very unhappy with the way the investigation was going". Garment said.
For some, it raises new questions.
"I never thought he was in the loop to have the information," John Dean, counsel in Nixon's White House and the government's top informant in the Watergate investigation, said.
"How in the world could Felt have done it alone?"
Dean said he couldn't see how Felt, then in charge of the FBI's day-to-day operations, could have had time to rendezvous with reporters in parking garages and leave clandestine messages to arrange meetings. Perhaps FBI agents helped him, Dean suggested.
The scandal that brought Nixon's resignation began with a burglary and attempted tapping of phones at the Democratic Party offices at the
Watergate office building in Washington during Nixon's 1972 re-election campaign. It went on to include disclosures of covert Nixon administration spying on and retaliating against a host of perceived enemies.
But the most devastating disclosure was the president's own role in trying to cover-up his administration's involvement.
Among other things, Deep Throat urged Bob Woodward and Carl Bernstein to follow the money trail from the financing of burglars who broke into the Democratic National
Committee offices to the financing of Nixon's re-election campaign.
Woodward, Bernstein and Bradlee had kept the identity of Deep Throat secret at his request, saying his name would be revealed upon his death.
Even the existence of Deep Throat, nicknamed after an X-rated movie of the early 1970s, was kept secret for a time. Woodward and Bernstein
revealed their reporting had been
aided by a Nixon administration source in their bestselling book All the President's Men.
A hit movie was made of the book in 1976, starring Robert Redford and Dustin Hoffman, which portrayed the cloak-and-dagger methods employed by Woodward and Deep Throat.
When Woodward wanted a meeting, he would position an empty flowerpot containing a red flag on his apartment balcony. When Deep Throat wanted to meet, the hands of a clock would appear written inside Woodward's New York Times.
The identity of the source had sparked endless speculation over the past three decades. Dean, Nixon chief of staff Alexander Haig, White House press aide Diane Sawyer, speechwriter Pat Buchanan and even former President George Bush senior were among those mentioned as possibilities.
Felt also had been mentioned, but regularly denied it. His motive for tipping off Woodward and Bernstein remains unknown, but the Post suggested in a story on Tuesday night that anger over Nixon's decision to pass him over for FBI director after the death of J Edgar Hoover could have been a factor.
Initially, Nixon and his closest aides thought Felt's ambition might make him the ideal person to sidetrack an FBI investigation into the Watergate burglary.
Six days after the break-in, Nixon and his co-conspirators discussed ordering the FBI to close its probe, on the grounds the inquiry would interfere with a CIA operation.
"Mark Felt wants to cooperate because he's ambitious," White House chief of staff HR Haldeman said.
"Yeah," the president replied.
They could not have been more wrong.
Felt had expressed reservations in the past about revealing his identity, and about whether his actions were appropriate for an FBI man, his grandson said. His family members thought otherwise.
His daughter, Joan, argued he could "make enough money to pay some bills, like the debt I've run up for the children's education".
Woodward and Bernstein were the first reporters to link the White House and the Watergate break-in.
Nixon, facing impeachment for helping to cover up the break-in, resigned in August, 1974.
Forty government officials and members of Nixon's re-election committee were convicted on felony charges.
However, Felt himself was convicted in 1980 for authorising illegal break-ins in the 1970s at homes of people associated with the radical anti-Vietnam group Weather Underground.
He was pardoned by President Ronald Reagan in 1981.
Felt had argued he was authorised by his boss, Patrick Gray the man given the job Felt had coveted who approved the break-ins without first going to court for a warrant.