With the recently busted Russian spy ring collecting no information of actual value and having no real access to policymakers, I often asked myself how they got caught in the first place. Stratfor (search for the article title on Google to access for free) thinks it has the answer:
The criminal complaint did not suggest how the U.S. government came to suspect these people of reporting back to the SVR in Russia, although we did notice that the beginning of the investigation coincides with the time that a high-level SVR agent stationed at Russia’s U.N. mission in New York began passing information to the FBI. Sergei Tretyakov (who told his story in the book by Pete Earley called “Comrade J,” an abbreviation of his SVR codename, “Comrade Jean”), passed information to the FBI from the U.N. mission from 1997 to 2000, just before he defected to the United States in October 2000. According to the criminal complaint, seven of the 11 suspects were connected to Russia’s U.N. mission, though evidence of those links did not begin to emerge until 2004 (and some as late as 2010). The timing of Tretyakov’s cooperation with the U.S. government and the timing of the beginning of this investigation resulting in the arrest of the 11 suspects this week suggests that Tretyakov may have been the original source who tipped off the U.S. government. So far, the evidence is circumstantial — the timing and the location match up — but Tretyakov, as the SVR operative at Russia’s U.N. mission, certainly would have been in a position to know about operations involving most of the people arrested June 27.
This poses another question, though: if the Russians knew he defected and knew knew that he knew about the illegal program, why didn't they dismantle it? I can think of a few explanations: they didn't know he knew, they're incompetent, or they're playing a deeper game and did this all on purpose.