Jennifer Lynne Matthews, 45, whose name has not previously been made public, was among seven agency operatives slain by an informant who set a trap after claiming to have infiltrated al-Qaeda's innermost circle.

Matthews had been one of the CIA's top experts on al-Qaeda and a veteran targeteer in the agency's air war against terrorist groups. A Fredericksburg resident with three school-age children, she had served for seven months at the helm of a CIA forward operating base in the turbulent Khost province when the attack occurred.

The identities of Mathews and another CIA officer killed in the attack, Darren LaBonte, 35, formerly of Alexandria, had been officially secret until Monday's memorial service. The names of the five others killed at Khost, the deadliest single attack on the spy agency in 25 years, were previously disclosed.

In keeping with a four-decade tradition, agency Director Leon E. Panetta presided over the formal unveiling of the 12 stars on the CIA Memorial Wall at the entrance to the agency's Langley headquarters, according to those present. Panetta lauded the 12 as "heroes" and "silent warriors" who had helped protect the country, even though most Americans would never know exactly how or where they served.

"Whether their names are known to the world or only to us, each cherished colleague remains a constant source of inspiration and courage," he said.

In addition to the seven Americans killed at Khost, the 12 dead included five killed elsewhere while conducting clandestine assignments in recent years. Their identities remain secret. The CIA has not officially released any of the 12 names.

With the new additions, the Memorial Wall has 102 stars designating officers and contract employees killed on the job since 1947. A leather-bound volume beneath the display lists 62 names; the 40 others are denoted only by a gold star and a blank space.

Matthews is among the few agency women to be killed on duty. Fellow officers remembered her as a passionate analyst, among the first to specialize in the study of an obscure group of pan-Arab terrorists who called themselves "the Base," or al-Qaeda.

"She was one of the most deeply substantive experts we ever had on the subject," said a former senior intelligence official who worked closely with her.

The official, who spoke on the condition of anonymity because the agency had not formally released the officer's name, described as her defining feature an "agile mind, always willing to open a door and look at it in a different way."

Matthews had worked in the Osama bin Laden unit, known as Alec Station, and also served a brief stint in London.