Never never never talk to the FBI without an attorney present. Never.
Same is true for all police interviews. 90% of everything the police have to prove in a criminal case is admitted, inadvertently, by a defendant before he knows he is a defendant and before he is read his rights.
The simplest of things can be pretty thorny to prove in a trial.
Proving “Joe is my cousin” can be a lot of work if the defendant did not say it. I saw a domestic violence case dismissed over whether the couple were actually married because the Probate Court Clerk failed to show up to authenticate the marriage certificate. And the lawyer (not me) had rfused any interviews.
No interviews with police of prosecutors, ever. Let the lawyer carry the message both directions.