SAN FRANCISCO - W. Mark Felt, 95, the former FBI second-in-command who revealed himself as "Deep Throat" 30 years after he helped the Washington Post unravel the Watergate scandal, has died.

Mr. Felt died Thursday at home in Santa Rosa under hospice care after suffering from congestive heart failure for several months, said family friend John D. O'Connor, who wrote a Vanity Fair article disclosing Mr. Felt's secret in 2005.

The shadowy central figure in one of the most gripping political dramas of the 20th century, Mr. Felt insisted his alter ego be kept secret when he leaked information to Post reporter Bob Woodward.

The scandal led to President Richard Nixon's resignation in 1974, two years after the break-in at the headquarters of the Democratic National Committee in the Watergate office building in Washington.

While some - including Nixon and his aides - speculated that Mr. Felt was Deep Throat, he steadfastly denied the accusations until finally coming forward in May 2005.

"I'm the guy they used to call Deep Throat," Mr. Felt told O'Connor for the Vanity Fair article, creating a whirlwind of attention.

Critics, including those who went to prison for the Watergate scandal, called him a traitor to the commander in chief. Supporters said he was a hero for blowing the whistle on a corrupt administration.

"This is a man who did his duty to the Constitution," Woodward said in an interview.

Mr. Felt had agonized about what revealing his identity would do to his reputation. Would he be seen as a turncoat or a man of honor?

"People will debate for a long time whether I did the right thing by helping Woodward," Mr. Felt wrote in

A G-Man's Life: The FBI, 'Deep Throat' and the Struggle for Honor in Washington

, his 2006 memoir. "The bottom line is that we did get the whole truth out, and isn't that what the FBI is supposed to do?"

Ultimately, his daughter, Joan, persuaded him to go public; after all, she argued, Woodward was sure to profit by revealing the secret after Mr. Felt died. "We could make at least enough money to pay some bills, like the debt I've run up for the kids' education," she told him, according to the Vanity Fair article.

It was by chance that Mr. Felt came to play a pivotal role in the Watergate drama.

Back in 1970, Woodward struck up a conversation with Mr. Felt while both were waiting in a White House hallway. Mr. Felt apparently took a liking to the young Woodward, then a Navy courier, and Woodward kept the relationship going, treating Mr. Felt as a mentor as he tried to figure out the ways of Washington.

Later, while Woodward and his Post colleague, Carl Bernstein, relied on various sources in reporting on Watergate, the man their editor dubbed "Deep Throat" - after the title of a notorious porn movie - helped to confirm vital information. The Post won a Pulitzer Prize for its Watergate coverage.

In his memoir, Mr. Felt wrote that he was upset by the slow pace of the FBI investigation into the Watergate break-in.

"From the start, it was clear that senior administration officials were up to their necks in this mess," he wrote.

Some critics said Mr. Felt, a J. Edgar Hoover loyalist, was bitter at being passed over when Nixon appointed an FBI outsider and confidant, L. Patrick Gray, to lead the FBI after Hoover's death.

Mr. Felt said he wasn't motivated by anger or jealousy.

Gray was later implicated in Watergate abuses.