One of the final testing grounds for disguises specially designed for the CIA's operations officers — particularly those still coming begrudgingly to terms with wearing wigs and prostheses — was centrally located and usefully crowded, according to the agency's former chief of disguise, Jonna Mendez.

"We would send them to the cafeteria at the agency," she said. "We'd send them down to go have lunch with everyone who knew them: their boss, their peers, their subordinates. Everybody was there."

"And that could be a very come-to-Jesus moment," she said. "When they discovered that nobody paid any attention."

In an interview with "Intelligence Matters" host and CBS News senior national security contributor Michael Morell, Mendez, who spent nearly 30 years at the agency before retiring in 1993, said the disguises she and teams around the world would create in the agency's Office of Technical Service could be life-saving.

"We disguised any intelligence officer or asset who had a need, either for deniability [or] possibly for personal-safety reasons, in order to be able to step away from a surveillance situation," she told Morell. "There were lots of situations where disguise was the obvious remedy."

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One of them, she said, included handling so-called "walk-ins" — potential but untested agents who enter an embassy to volunteer information. Intelligence officers can often take the first meeting.

"It quickly became apparent, when terrorism started raising its head, that those officers needed protection, when they're walking down and meeting with you-don't-know-who, and you don't really understand, initially, what their intent is," Mendez said. "So we used with them what we would call light disguise" — just enough to mask their identities without being unduly elaborate.

"It was enough to conceal who they were, when they walked out of the embassy at the end of the day," she continued, "and somebody would not follow them home, for instance, and see where their house was and see where their family lived and set them up for something untoward."

Disguises used by the agency could involve typical props — wigs, beards, masks, or fake ears — but more sophisticated techniques have also evolved, Mendez said.

"We have people who have chemistry backgrounds, who evaluate materials for us, who actually invent materials for us," she told Morell. After modeling some disguises on Hollywood masks, which were usually made of latex, Mendez said, the CIA soon sought out better techniques.

Latex masks, she explained, "were uncomfortable. They didn't breathe. If you were in a climate with any humidity, they were suffocating."

"So we went off chasing other materials that would animate more, that were breathable, that were easy on, easy off," Mendez said.

Hair posed a similar problem. "We like to use real hair," Mendez said, "But that's a problem, especially if there's humidity. So then we use Kanekalon and things like that," she said, referring to a synthetic material typically used in hair extensions.

"And then there's a problem, security-wise. Because if you look at it with infrared, it looks like a glowing snow cone on your head," she explained. "We were always chasing down those kinds of things."

Mendez also discussed her marriage to Tony Mendez, a celebrated former CIA officer and master of disguise who was famously portrayed in the Oscar-winning film "Argo." The two had met while on assignment overseas and been married for nearly 30 years.

They had just finished working together on a new book, "The Moscow Rules," about their time spying in Russia during the Cold War when Tony passed away last January.

"Tony always said that working at the CIA was drinking from a firehose, and that retiring was like jumping from a moving train," Mendez said. "I think what Tony and I have tried to do is open it up enough where young people could consider, maybe, this kind of work, government work, as honorable work."

"Now, I know that CIA has 50,000 applicants a year," she continued. "They are not worried about getting to the bottom of the barrel."

"But we just like to encourage people to consider it as a career option."

For much more from Michael Morell's conversation with Jonna Mendez, including highlights from her new book, "The Moscow Rules," you can read the transcript here and subscribe to "Intelligence Matters" here.