However, he also became the highest-ranking FBI official ever convicted of a crime — for ordering break-ins in the 1970s of people possibly connected to the Weather Underground, a group claiming responsibility for many bombings (including at the U.S. Capitol and Pentagon). Felt said the break-ins were essential for national security and Ronald Reagan later pardoned him.

Nixon chief counsel Charles "Chuck" Colson worked closely with Felt in the Nixon administration and expressed surprise at the disclosure.

"Mark first served this country with honor, and I can't imagine how Mark Felt was sneaking in dark alleys leaving messages under flower pots and violating his oath to keep this nation's secrets. I cannot compute that with the Mark Felt that I know," Colson told the AP. Colson pleaded no contest to an obstruction of justice charge in the Watergate scandal and served time in prison.

Another Nixon associate who wound up behind bars, G. Gordon Liddy, said he didn't consider Felt a hero for going to the Post reporters.

"If he were interested in performing his duty, he would have gone to the grand jury with his information," Liddy, who was finance counsel at Nixon's re-election committee and helped direct the break-in, said in an interview on CNN.

The FBI declined to comment Tuesday on Felt's admission.

Felt — who was born and raised in Twin Falls, Idaho, and had worked for two Democratic U.S. senators from Idaho before joining the FBI — headed the FBI's Salt Lake City office from 1956 to 1958.

"In less than three seconds, Agent Felt drew his pistol and emptied all six bullets into the dead center of the close-range target," said a 1958 Deseret News feature about him and about how tests at the time showed "the average agent today can out-draw and out-shoot any gunslinger of the old West."

Another old story told how he went to unusual lengths to arrest a bank robber in Utah. Felt was tipped off that the man was working a highway construction job near Blanding.

"To get to this remote part of the state, he used a chartered plane, which landed on the road the bank robber was helping to build," the story said.

Felt was transferred from Salt Lake City to Missouri, where he helped curb mobsters in the Kansas City mob as that city's special agent in charge. In 1962, he became head of the inspection division of the FBI. And in 1971, he became the No. 2 person at the FBI behind Hoover.

The Vanity Fair article says Felt aided Woodward and Bernstein because he felt it was the only way to fight corruption in the White House and the Justice Department, but that he was conflicted about it.

The magazine quoted his son, Mark Jr., as saying, "His attitude was: I don't think (being Deep Throat) was anything to be proud of. You should not leak information to anyone."