A long-time Washington guessing game ended in May. The family of retired FBI official W. Mark Felt announced that he was Deep Throat, the celebrated anonymous source for a newspaper series covering the Watergate scandal in the early 1970s. With Mr. Felt's help, Washington Post reporters Bob Woodward and Carl Bernstein investigated the cover-up of illegal campaign activities that led President Richard Nixon to resign from office in 1974. Now Mr. Woodward offers his perspective on that relationship in a new book called The Secret Man: The Story of Watergate's Deep Throat.

Bob Woodward and Carl Bernstein wrote about Deep Throat in their 1974 book about Watergate, called All the President's Men. He also appeared in the movie version of the book, portrayed by Hal Holbrook as an unnamed figure wrapped in shadows. But for more than 30 years, Bob Woodward stuck to his vow to reveal Deep Throat's identity only after his death.

Bob Woodward Tells Story of Anonymous Watergate Source

Once the secret was out, he rushed into publication the book he had been holding back for years. He told NBC News that he could finally tell "the very complicated three-decade story that involved lots of uncertainty and anguish." And he suggested that the story has contemporary relevance as well. "In a time of security and surveillance," said Mr. Woodward, "which is the period we live in after 9-11, for reporters to be able to have a confidential source like that, somebody who really knows what's going on in the center of things, that's vital."

Bob Woodward Tells Story of Anonymous Watergate Source

In The Secret Man, Bob Woodward describes how he first met Mark Felt in a White House waiting room in 1969. Then a young Navy lieutenant, Mr. Woodward was there to deliver a package. Mr. Felt was an assistant FBI director, and soon became a career mentor to the young Woodward. On June 17, 1972, 5 men were arrested for burglarizing Democratic National Committee offices in Washington's Watergate office building. By now a Washington Post reporter, Bob Woodward and his partner Carl Bernstein painstakingly pieced together a story involving attempted eavesdropping and sabotage of Democratic Presidential candidates.

Bob Woodward Tells Story of Anonymous Watergate Source

Mr. Woodward writes that his secret conversations with Mark Felt confirmed information the 2 reporters already suspected, or directed them to new leads. The FBI official's motives for providing that help were complex, Mr. Woodward told CBS News. "He clearly saw lots of lawbreaking in the Nixon White House," Mr. Woodward said. "He didn't like the fact that the Nixon White House was trying to push the FBI around and politicize it. He was also upset that he had not been made director of the FBI after Hoover died. But, by and large, Mark Felt and the other sources Carl Bernstein and I had had it right. In fact, they understated the level of criminality in the Nixon White House."

Mark Felt had worked in espionage surveillance earlier in his FBI career, and his dealings with Bob Woodward acquired all the trappings of a high-stakes spy drama. The young reporter would move a flower pot containing a red flag to the back of his apartment balcony when he wanted to arrange a meeting with Mr. Felt. Those meetings took place in the dead of night in a parking garage. As the number two man at the FBI, Mark Felt was taking risks Bob Woodward calls "immense." "That's why he insisted that we have these really extraordinary and unheard-of clandestine meetings in an underground parking garage," Mr. Woodward says. "What he wanted to do is guarantee that he would not be fingered, that I would protect him and no one else would know."

A Washington Post editor nicknamed Mark Felt Deep Throat, inspired by the title of a pornographic movie of the time. The name was a play on the journalistic term "deep background," meaning information used in a news report without identification of the source. Mark Felt was determined to make sure he remained unidentified, even after the Watergate story broke. "When Carl Bernstein and I wrote All the President's Men, we wanted to disclose his identity," Mr. Woodward recalls. "Felt absolutely insisted, no. It turned out later he was investigated and prosecuted for authorizing break-ins by the FBI, so there are lots of ironies in this story, and lots of anguish also."