Is it true that the old KGB files are now closed to researchers?
Yes. French researchers went in very quickly after the Soviet union fell and grabed as much information from KGB files as they could. They wrote the “Black book of communism” from some of what they found. It catalogues data. Also information was found on communist spies in the communities and families who were informants on their own families and friends.
Apparently there is information on KGB relationships with American and European spies...but I think the Left in both countries have managed to cover that information up pretty well. Now the filed are closed to public viewing.