At the time of his defection on Oct. 11, 2000, Mr. Tretyakov allegedly had been working as a double agent for the United States for three years while he was the SVR’s second-in-command in New York. From 1995 to 2000, he oversaw all Russian covert operations in the city and had more than 60 intelligence officers under his command, according to [a book by Pete Earley on Tretyakov].