Well, this is interesting. I forgot the Hanssen prosecutors used a Russian dossier against Hanssen.
How FBI paid $12m to unmask a traitor Robert Hanssen
The New York Times ^ | October 19 2002 | By David Johnston in Washington
http://www.freerepublic.com/focus/f-news/772298/posts
http://www.smh.com.au/articles/2002/10/18/1034561314721.html
The FBI paid $US7 million ($12.7million) to a former Russian intelligence officer to smuggle out of Moscow a secret KGB file that unmasked a veteran FBI agent as a spy for Russia, according to a new book about the case.
Although it was known that the FBI got the file from a Russian source, it was not known just how much it cost the bureau to find the agent, Robert Hanssen, or that the former KGB officer, whose name is not disclosed in the book, was secretly relocated to the United States.
...
Gen. Drozdov, 67, once a feared and respected KGB leader, gave up a quiet retirement to form the business consulting firm Namakon earlier this year with two KGB veterans. . .Namakon is also considering cooperative ventures with former CIA counterterrorist official Vincent Cannistraro, now a private consultant, and with Mr. Burke's Parvus-Jericho, whose staff includes numerous former U.S. intelligence officials.