Earlier quoted context omitted.
1 or 2 months later an offer of employment (to a Canadian!) arrived at his doorstep. This is a standard way to catch people who do this type of stuff. Once he sets foot on American soil, he would be arrested. You actually have to be pretty dense to fall for it. ~99% of employment at the CIA requires some form of security clearance, which in turn requires you to be a US citizen.
While I see the point, I'm not sure I believe you that easily. Not all clearance forms require you to be a citizen (besides there must be some way to cooperate with companies from other countries). Why are you sure he would get arrested? Has there been a documented case of something like that happening before? Isn't the offer of employment an official document that's legally forcing to hire someone if they accept? (n…
Also, I'm fairly certain you are incorrect about security clearances (at least for Confidential, Secret, and Top Secret). Even dual citizens have to shred their extra passport and renounce their additional citizenship. The FBI website mentions that for Top Secret, citizenship is verified through investigation: "For a Top Secret security clearance, the background investigation includes additional record checks which can verify citizenship...." [2] If you're working at an intelligence agency like the CIA, Top Secret is pretty much required.
[1] http://www.pcworld.com/article/173397/uks_high_court_rejects...