Freda Underhill, referring to the FBI's visits, presumably to interview Berg, said "such visits are bound to have been recorded but no transcripts have been produced."

The FBI, at least in normal criminal operations inside the US, does not record interviews. Two agents (at least) will be present at the interview. This serves two purposes: One is free to make thorough notes while the other conducts the interview; and if the agents' account is challenged, it's two people's word against one.

Of course I can't guarantee that this regular procedure was used with Berg, but I'd bet money on it.   In any case, "such visits are bound to have been recorded" is clearly erroneous.

Dave Oesterreich