Via Newsweek and based on a new audio-only book:
Now we know, according to an posthumously published book by the late David Wise, the authoritative espionage writer who died from pancreatic cancer last month. The informant, Wise writes, was Alexandr Shcherbakov, a down-on-his-luck former KGB officer who delivered the Kremlin’s dossier on Hanssen to an FBI counterspy who had pursued the case for years.
Link:https://www.newsweek.com/who-dimed-o...anssen-1196080