W. Mark Felt, the former FBI second-in-command who revealed himself as "Deep Throat" 30 years after he tipped off reporters to the Watergate scandal that toppled U.S. President Richard Nixon, has died. He was 95.

Felt died Dec. 18 of congestive heart failure, said John D. O'Connor, a family friend who wrote the 2005 Vanity Fair article uncovering Felt's secret.

The shadowy central figure in one of the most gripping political dramas of the 20th century, Felt insisted his alter ego be kept secret when he leaked damaging information about Nixon and his aides to The Washington Post.

While some — including Nixon and his aides — speculated that Felt was the source who connected the White House to the June 1972 break-in at the headquarters of the Democratic National Committee, he steadfastly denied the accusations until finally coming forward in May 2005.