Finn Teller is a security consultant with the SIA.
In the blurbs I have seen for this person's adventures, I have see the title "corporate spy" used but to me that immediately evokes the idea of someone hired by Company A to infiltrate Company B and steal B's trade secrets to the detriment of B and the increased profits of A. That is definitely not the sort of work that Teller does.
On the other hand, she does works for a private corporation, not a government agency so the adjective is correct. And she does all the same sort of things that any good operative would be expected to do so the noun is apt. Still, I eschew the moniker.
When we first meet her, she is an employee of the SIA, or Strategic Information Associates. It was started by, and still run by, Jon McAuliffe, a former CIA operative who, upon retirement, used his contacts to create his own private enterprise and proved to be extremely successful at it.
"The company's name, always spoken letter by letter, wasn't an accident. SIA was an international for-hire agency that did a lot of the same work for multinationals, hedge funds, and oligarchs that the CIA did for the US government. It was staffed by analysts, operatives, and former military people, many of them retired-in-their-prime veterans schooled in the arts of detection and deception by domestic and foreign government agencies.
"Body language experts vetted prospective jurors and CEO candidates. Techies developed corporate security systems. Former covert operatives ferreted out internal corruption; uncovered secrets buried in the pasts of job applicants, boardroom rivals, and investment targets; dug up dirt on competitors; and tracked down disgruntled employees or competitors who'd stolen client lists and prototypes of new technology.
"The firm had a black-ops division, too - kidnap recoveries, terrorist interrogations, political espionage, and unauthorized looks at a competitor's R&D. SIA even worked for governments, secretly doing what the authorities couldn't because it might break the law or rile a trading partner."
Teller is one of McAuliffe's best operatives since the day several years before that she left her previous employer of a handful of years, the CIA. She had been a rising star in that agency as well until a mission ended badly because it was expedient for her superiors to ignore her warnings. Angered, she quit. Almost immediately, McAuliffe offered her a lucrative position and she has happily stayed in it.
Teller is very good at the black-ops work when it is necessary - she is an ardent student of Krav Maga and not too shabby with firearms - but she also gets involved in the other divisions because besides being quite intelligent and resourceful, she has an almost uncanny skill at detecting lies. Her abilities in interrogations, picking up on the signs of deception as well as just hedging an answer, is what made her so good with the CIA and what is now so valuable to the SIA.
It is also one of the main reasons why she is still single. It's impossible to enjoy the sweet nothings whispered by a would-be suitor when you know instantly they are a lie.