NEW YORK — AOL's chief technology officer left the company and two other workers were fired in the aftermath of a privacy breach that involved the intentional release of more than 650,000 subscribers' Internet search terms.

Although AOL had substituted numeric IDs for the subscribers' user names, the search queries themselves contained Social Security numbers, medical conditions and other data that could be traced to an individual. In fact, The New York Times was able to trace user 4417749 to Thelma Arnold, 62, of Lilburn, Ga.

Maureen Govern, the technology chief, will be replaced on an interim basis by John McKinley, who had held that position before becoming AOL's president for digital services. The change takes effect immediately, according to a memo AOL Chief Executive Jonathan Miller sent to employees yesterday.

"This incident took place because some employees did not exercise good judgment or review their proposal with our privacy team," Miller said in a second memo. "We are taking appropriate action with the employees who were responsible."

The data release is among a series of breaches involving sensitive information in recent months. Unlike those resulting from computer hacking or missing laptops, however, the AOL data had been intentionally released as part of a program to assist academic researchers.

AOL, a unit of Time Warner Inc., apologized two weeks ago for what it termed a mistake made by a company researcher who had failed to properly seek clearances before releasing three months' worth of search data. Though the information was meant for researchers, it was released to a public site and quickly circulated once a blogger discovered it.

The company fired the researcher who released the data and that employee's direct supervisor, who reported to Govern, said one person familiar with the company's decisions. The person, who spoke on condition of anonymity because release of personnel information was not authorized, would not say whether Govern's departure was voluntary.

The person also would not identify the two employees who were fired.

Although the search terms released were not directly tied to real names, many individuals type their own names to find out what's being said about them. They may later search for online mentions of their credit card or Social Security numbers and perhaps for prescription drug prices, revealing their medical ailments. All the searches for each user name were linked to the same numeric ID in the released data.

AOL removed the information from its site once senior executives learned of it, but by then copies already were widely available. Some people even created search sites just for the AOL data.

The fallout occurs as AOL tries to lure more people to its search services and other free, ad-supported features to offset a revenue decline that's likely to accelerate as the company stops charging for AOL.com e-mail accounts and software.

AOL continues to rank fourth in search, behind Google Inc., Yahoo Inc. and Microsoft Corp.'s MSN, according to data released this week by Nielsen/NetRatings and comScore Media Metrix.