In late 2007, there was the first crack of daylight into the government's use of waterboarding during interrogations of Al Qaeda detainees. On Dec. 10, John Kiriakou, a former C.I.A. officer who had participated in the capture of the suspected terrorist Abu Zubaydah in Pakistan in 2002, appeared on ABC News to say that while he considered waterboarding a form of torture, the technique worked and yielded results very quickly.
Mr. Zubaydah started to cooperate after being waterboarded for "probably 30, 35 seconds," Mr. Kiriakou told the ABC reporter Brian Ross. "From that day on he answered every question."
His claims - unverified at the time, but repeated by dozens of broadcasts, blogs and newspapers - have been sharply contradicted by a newly declassified Justice Department memo that said waterboarding had been used on Mr. Zubaydah "at least 83 times."
Some critics say that the now-discredited information shared by Mr. Kiriakou and other sources heightened the public perception of waterboarding as an effective interrogation technique. "I think it was sanitized by the way it was described" in press accounts, said John Sifton, a former lawyer for Human Rights Watch, an advocacy group.
During the heated debate in 2007 over the use of waterboarding and other techniques, Mr. Kiriakou's comments quickly ricocheted around the media. But lost in much of the coverage was the fact that Mr. Kiriakou had no firsthand knowledge of the waterboarding: He was not actually in the secret prison in Thailand where Mr. Zubaydah had been interrogated but in the C.I.A. headquarters in Northern Virginia. He learned about it only by reading accounts from the field.
On "World News," ABC included only a caveat that Mr. Kiriakou himself "never carried out any of the waterboarding." Still, he told ABC that the actions had "disrupted a number of attacks, maybe dozens of attacks." A video of the interview was no longer on ABC's website.
"It works, is the bottom line," Rush Limbaugh exclaimed on his radio show the next day. "Thirty to 35 seconds, and it works."
Mr. Kiriakou subsequently granted interviews to The Washington Post, The New York Times, National Public Radio, CBS, CNN, MSNBC and other media organizations. A CNN anchor called him "the man of the hour."
Eight months after the interview, Mr. Kiriakou was hired as a paid consultant for ABC News. He resigned last month and now works for the Senate Committee on Foreign Relations.
His ABC interview came at an especially delicate juncture in the debate over the use of torture. Weeks earlier, the nomination of Michael Mukasey as attorney general was nearly derailed by his refusal to comment on the legality of waterboarding, and one day later, the C.I.A. director testified about the destruction of interrogation videotapes. Mr. Kiriakou told MSNBC that he was willing to talk in part because he thought the C.I.A. had "gotten a bum rap on waterboarding."
At the time, Mr. Kiriakou appeared to lend credibility to the prior press reports that quoted anonymous former government employees who had implied that waterboarding was used sparingly. In late 2007, Mr. Ross began pursuing Mr. Kiriakou for an interview, "leaning on him pretty hard," he recounted.
On Dec. 10, in the subsequent interview, Mr. Kiriakou told Mr. Ross that he believed the waterboarding was necessary in the months after the 9/11 attacks. "At the time I was so angry," he told Mr. Ross. "I wanted so much to help disrupt future attacks on the United States that I felt it was the only thing we could do."
Mr. Kiriakou was the only on-the-record source cited by ABC. In the televised portion of the interview, Mr. Ross did not ask Mr. Kiriakou specifically about what kind of reports he was privy to or how long he had access to the information. "It didn't even occur to me that they'd keep doing" the waterboarding, Mr. Ross said last week. "It doesn't make any sense to me."
He added, "I didn't give enough credit to the fiendishness of the C.I.A."
Mr. Kiriakou refused an interview request last week. In a statement to ABC, he said he was aware only of Mr. Zubaydah's being waterboarded "on one occasion."
The C.I.A., which considered legal action against Mr. Kiriakou for divulging classified information, said last week that he "was not - and is not - authorized to speak on behalf of the CIA."
Paul Gimigliano, a C.I.A. spokesman, said: "This agency did not publicly disclose the frequency with which the waterboard was used, noting only that it was employed with three detainees. If reporters got that wrong, they weren't misled from here."
In the days after Mr. Kiriakou's media blitz, his claims were repeated by an array of other outlets. For instance, the Fox News anchor Chris Wallace cited the 35 seconds claim to ask a congressman whether the interrogation program was "really so bad."
Months later the claims continued to be amplified; the National Review editor Jonah Goldberg used Mr. Kiriakou's assertions in a column last year to argue that the waterboarding was "right and certainly defensible."
Mark Danner, a journalist who has written extensively about the covert program for The New York Review of Books, said the news reports had fed the idea that brutal interrogations could instantly glean information about terrorist plans.
"There was a completely mistaken impression put about that this technique was not cruel because it could break detainees so quickly," he said.
(An article in The New York Times on Dec. 13, 2007 described his comments to ABC and added a quotation from Mr. Kiriakou: "I think the second-guessing of 2002 decisions is unfair. What I think is fair is having a national debate over whether we should be waterboarding.")
When Mr. Kiriakou was later hired by ABC to provide commentary on terrorism cases, Mr. Ross said that network officials had been concerned about the appearance of a tie between the interview and the job. For that reason, "I felt that we should sort of wait," he said. "I didn't want anyone to think that he was promised something for the interview. He was not."
Mr. Ross, who received a George Polk Award for a series on interrogation, expressed no regret about the Kiriakou interview and praised him for speaking publicly. He said ABC was preparing a story that would address the previous reporting.
"Kiriakou stepped up and helped shine some light on what has happening," Mr. Ross said. "It wasn't the huge spotlight that was needed, but it was some light."
As talk continues about possible prosecutions of people involved in the interrogations, waterboarding is once again a hot topic. Last week, Sean Hannity, a conservative Fox News host, said he would agree to be waterboarded (for charity) when a guest proposed that he experience it.
But the recent Justice Department memo has led some commentators to revisit their earlier impressions about the technique.
"I've always been on the fence about whether waterboarding constituted torture," Mr. Goldberg of the National Review wrote last week, but if the figures are true, "then I think the threshold has been met."
He added: "Debating whether it was worth it still seems open to debate, depending on the facts."
Scott Shane contributed reporting from Washington.