Who helped topple the Nixon administration by steering two Washington Post reporters to the truth? Was it the Army general? The future president? An obscure lackey? Or no one at all?
Only a handful of people seem to know the identity of "Deep Throat," and some critics say the search for him - or her - is mere trivia. But that hasn't stopped legions of journalists, professors, and amateur theorists from trying to uncover the truth.
"Watergate isn't still fascinating. Not a whole lot of people are still reading or thinking about it. But Deep Throat has some kind of mystique," says Jim Doyle, who served as special assistant to the Watergate prosecutors.
So much mystique that the nation's political and media circles are still buzzing about new clues unleashed last weekend.
First, the University of Texas allowed visitors to examine more than 75 boxes of never-before-seen notes and files of reporters Bob Woodward and Carl Bernstein, including drafts of their famous book "All the President's Men."
Then, former Nixon aide John Dean resurfaced in a Los Angeles Times commentary, disclosing that he's heard - from an anonymous source, no less - that Deep Throat is ill. The reporters are expected to reveal Mr. Throat's identity upon his death.
But so far the three people who claim to have knowledge of Deep Throat's identity - the two reporters and their former editor, Ben Bradlee - aren't talking. They don't need to, according to current and former journalism students at the University of Illinois. They insist they've uncovered the identity of Deep Throat. He is, they say, former White House deputy counsel Fred Fielding, who most recently served as a member of the 9/11 Commission.
The students identified Mr. Fielding in 2003 after launching an extensive investigation into the mystery. But their target denied the accusation, and Mr. Bernstein reportedly rapped the class for trying to unveil a source.
Other top Deep Throat suspects include Nixon chief of staff Alexander Haig, Secretary of State Henry Kissinger, and speechwriters Patrick Buchanan and David Gergen. Even TV newswoman Diane Sawyer, then a White House aide, has found herself under suspicion.
It's possible that the reporters lied to protect their source's identity. Maybe Deep Throat wasn't a man, didn't drink Scotch, and didn't smoke, making Hal Holbrook's memorably menacing performance in the film "All the President's Men" a complete fiction. Then again, maybe he was a composite of several people.
Maybe, says leading Watergate scholar Stanley Kutler, it just doesn't matter. The guessing game "is just a fascination with celebrity culture," he says. "It's worth our while to understand Richard Nixon, not Woodward and Bernstein. How did we get a president who did all the things that he did?"
Mr. Dean, who has floated his own theories about Deep Throat's, agrees that the source's identity makes no difference in "the larger picture of Watergate." On the other hand, there aren't any more unsolved questions to solve, he says. "So rather than diverting attention, this mystery may be attracting some attention [to Watergate]."
For journalists, the new focus on Deep Throat couldn't have come at a better time. Prosecutors are targeting several reporters who won't disclose the names of their informants. "Thank God we have the example of Deep Throat we can point to," says Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press.
Without anonymous sources, "important stories that the public should know, and may change the course of history, would go untold, or told incompletely or incorrectly," says Clark Hoyt, Washington editor for Knight Ridder. He and a colleague won a Pulitzer Prize for exposing 1972 vice-presidential candidate Thomas Eagleton's history of psychiatric therapy. Mr. Eagleton soon bowed out, and his running mate, George McGovern, lost the election to Richard Nixon. And who was it who helped Mr. Hoyt set the stage for Nixon's victory? An anonymous tipster.