SANTA ROSA, Calif. - The Washington Post said Tuesday that a former FBI official, W. Mark Felt, was the confidential source known as "Deep Throat" who provided the newspaper information that led to President Nixon's impeachment and eventual resignation. The paper made its announcement on its Web site after Felt, 91 and living in California, talked to a lawyer who wrote a magazine article for Vanity Fair. "The No. 2 guy from the FBI, that was a pretty good source," said Ben Bradlee, who had been the key editor at the Post in the Watergate era.
http://news.yahoo.com/fc/us/richard_nixon Who was Deep Throat?
Deep Throat met with Woodward seven times between September 1972 and May 1973 to help the two reporters break several stories about the involvement of Nixon administration officials in the June 17, 1972, burglary of the Democratic National Committee headquarters at the Watergate office-apartment-hotel complex in Northwest Washington. (The burglars, who were seeking information that could be used against Democrats in the upcoming elections, were indicted later for conspiracy, burglary, wiretapping and planting secret listening devices.)
The Post’s stories, along with those of other newspapers and several rulings by Judge John Sirica, the chief judge for the U.S. District Court for the District of Columbia and the Watergate trials, led to televised hearings in the U.S. Senate about the break-in. From these, a riveted nation learned about an administration coverup of the break-in and a covert White House operation that engaged in burglary and political spying. The hearings were followed by impeachment proceedings by the Judiciary Committee of the House of Representatives. But before the full House could vote on whether the president should be impeached, Nixon resigned on August 9, 1974, and Vice President Gerald Ford was sworn in as president. At least 19 high-level officials and other conspirators would plead guilty to or be convicted of various crimes related to Watergate.
http://www.smithsonianmag.si.edu/smi.../presence.html 
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Deep Throat's identity revealed (Watergate scandal) 
