[Sniffnoy]

It's worse than that -- often their MO is to deliberately get people rattled so they say something false (that the FBI already knew was false), then charge them for that. It's stupid, but it's currently the [courts' interpretation of] the law. (The written law has a materiality requirement, but this has been interpreted so loosely as to be irrelevant.)

https://www.popehat.com/2017/12/04/everybody-lies-fbi-editio...

[kkielhofner]

With this law on the books they often operate under the same practice/advice you hear given to attorneys in court: "only ask questions you already know the answer to".

In many/most cases if they're asking questions they already know the truth behind at least some of them. They are attempting to leverage you into cooperating against co-conspirators or at least be able to hit you with a felony for misleading/false statements in the event the original investigation doesn't pan out to charges.