For 30 years, Nora Ephron told everyone her knowledge of the most famous anonymous source in the history of American journalism. Between 1976 and 1980, Ephron was married to Washington Post reporter Carl Bernstein, whom a few years earlier unhinged the presidency of Richard Nixon in exposing the 1972 burglary of Democratic headquarters by operatives of Nixon’s re-election campaign.

The crucial source in all that, of course, was nicknamed “Deep Throat,” and for more than three decades, people outside the circle of Bernstein and his colleague, Bob Woodward, guessed as to who inside the Nixon White House might have tipped off The Washington Post to the most famous bungled crime in U.S. political history.

Ephron, the writer and director who died yesterday from leukemia at age 71, was on the inside. For decades, she wrote in 2005, she carried the knowledge that Woodward’s anonymous source was FBI Associate Director Mark Felt. When Felt told Vanity Fair in 2005 that he had been Deep Throat, Woodward, Bernstein and their old editor, Ben Bradlee, finally broke their three-decade silence on the topic.

But Ephron wasn’t quiet all those years. Not that she was told directly. A few days after Felt came forward, Bernstein told The Today Show that it would have been foolish to share Deep Throat’s identity with Ephron, apparently out of fear that she would not keep the secret. “I was never dumb enough to tell her,” he said.

In her first of what would become hundreds of columns for The Huffington Post, Ephron agreed with that assessment. Instead, she deduced from the published clues about Deep Throat—male, high-ranking Justice Department official with access to both the president and the White House’s political operations—that it was Felt. And she told everyone she could:

I knew that Deep Throat was Mark Felt because I figured it out. Carl Bernstein, to whom I was married for a brief time, certainly would never have told me; he was far too intelligent to tell me a secret like that. He refused to tell his children too, who are also my children, so I told them, and they told others, and even so, years passed and no one really listened to any of us.

But it’s possible someone might have considered Ephron’s deductive reasoning. In December 1980, as Felt was due to be sentenced after being convicted of violating the civil rights of Weather Underground members, Post columnist Richard Cohen approached Woodward with the guess that Felt was Deep Throat and that he was ready to publish the big secret. Woodward recounted the meeting in The Secret Man, his 2005 confessional about Felt:

Around this time, Richard Cohen, a columnist for the Post and a good friend of Carl’s and mine, came to see me to say that he was prety sure Deep Throat was Mark Felt. Nora Ephron, Carl’s soon to be ex-wife, was on the case and she too was convinced it was Felt, Cohen said. He was going to write a column about this.

…

Look, he said, he had heard from someone—Carl or Nora or someone—that at the top of my Deep Throat memos were the initials “M.F.”—obviously Mark Felt, right?

Woodward wrote that he lied to cover Felt and Cohen spiked the column. Still, Ephron—if she was indeed Cohen’s source—was one of the first outside of Felt, Woodward, Bernstein and Bradlee to know the truth.

In that Huffington Post column recounting her knowledge of Watergate, Ephron does come off like a bit of a blab, though she prefaced her confession with the assertion that, “Not for nothing is indiscretion my middle name.”

When it came to Ephron’s own final days, that much turned out to be the opposite. Her battle with leukemia was fully shielded from the public view until the last moments.