President Clinton's order to declassify all U.S. government documents on human rights abuses and political violence in Chile has forcefully recalled the most painful period in agency history.

It is a cautionary tale of secrets and lies, burned deep into the CIA psyche. It begins on Feb. 7, 1973, with the question that Sen. Stuart Symington put to former CIA director Richard Helms before the Senate Foreign Relations Committee:

"Did you try in the Central Intelligence Agency to overthrow the government of Chile?"

"No, sir," Helms replied.

The facts told a different story, and three months later, after an order came down asking all CIA employees to report any evidence they had of any unlawful acts, someone at Langley questioned the truthfulness of Helms's response.

His prevarication found its way into a 693-page compendium of CIA misdeeds that was being compiled by the new director of central intelligence, William Colby--a document that came to be known as "the Family Jewels."

The Family Jewels told all: of plots to assassinate foreign leaders, overthrow governments, bug journalists, test psychedelic drugs on unwary subjects. And, of course, of the agency's efforts to destabilize the socialist regime of Chilean President Salvador Allende.

Colby shared the Family Jewels with Congress, the White House and, to a lesser extent, the news media. He hand-delivered a chapter to the Justice Department that directly led to Helms facing criminal charges over his Chile testimony. And Colby's revelations prompted the creation of the Senate Select Committee to Study Government Operations with Respect to Intelligence Activities, known as the Church Committee after its chairman, Sen. Frank Church.

Once the committee issued its final report, the CIA's ability to do pretty much as it pleased without telling anyone was over: Both houses of Congress created standing select committees to oversee the CIA as a full-time pursuit.

To this day, Helms--who pleaded no contest in 1977 for failing to testify fully to Congress, was ordered to pay a $2,000 fine and was given a two-year suspended sentence--remains one of the most revered figures in the secrecy-based CIA culture. (At 86, he is currently working on his memoirs.) But Colby, who died in 1996, is deeply resented by many for what is seen as betrayal.

"The first principle of a secret intelligence service is secrecy," Thomas Powers wrote in his 1979 biography of Helms, "The Man Who Kept the Secrets."

"It was bad enough this ancient history was being raked up at all, but to have it raked up in public, with all the attendant hypocrisy of a political investigation conducted by political men . . . This, truly, in Richard Helms' view, threatened to destroy the agency he and a lot of men had spent their lives trying to build."

Whether a new spirit of openness prevails at the CIA remains to be seen, at least when it comes to Clinton's declassification order on Chile. No covert action documents relating to CIA operations in Chile have yet been made public. But CIA spokesman Mark Mansfield said their release is only a matter of time.

"We're still very much in the middle of this, and we are going to be as forthcoming as possible," Mansfield said, "consistent with protecting legitimate intelligence sources and methods."

Vernon Loeb covers national security issues for The Post.