“The FBI was able to uncover Buryakov, along with two alleged accomplices, by employing an undercover agent of its own and allowing the Russians to ‘recruit’ their spy, according to a release by the Department of Justice. The ‘dangle,’ as the agent is known in espionage parlance, had posed as an analyst for a ‘New York-based energy company.’
From then on, the FBI was able to gather information through the undercover agent, including by planting listening devices in ‘binders containing purported industry analysis’ that were taken inside the SVR’s offices, the DOJ said.”
Source: Russian Spy Pleads Guilty, Walked Into FBI ‘Trap’ – ABC News