I think I'll modify what I said. Get a lawyer first if you can afford it. If not, you can consider going in and seeing why the FBI want to talk with you. But if you do that, DO NOT say anything whatever to them. Do not let yourself be provoked into defending yourself, excusing yourself, or saying anything else. If you are not prepared to hire a lawyer beforehand and take him with you, then it's important not to be tricked into saying anything at all.
ANYTHING whatever that you say can be used against you. And lying to the FBI (which you might do inadvertantly) was the offense that got Martha Stewart a jail term.
Gotcha. Thanks.