So... I like spy novels and such and I've always wondered how the hell one would keep it a secret which 50% of an embassy are secret service. So many possible patterns! Turns out, one doesn't, unless extremely careful. I also seem to remember that "who is secret service at the embassy" was never an important line of defense against counterespionage, something the article doesn't mention.
If you ask someone who can't tell you what they do, what they do, they'll give you a quick and really dull answer. Anyone implying that they "can't really talk about that" is most likely a service-desk technician.
The CIA did try to recruit him--it had geologists--it had more or less everybody. But it was known for cheaping out on technical staff, offering them a GS-x, then, when the scientist had left the old job and was in town, saying that the budget had been cut--which never, ever, happened in those days--and offering instead a GS-(x-2).