If you are approached and questioned by a Special Agent, ask for his or her business card. Firmly but politely state that you do not want to answer any questions, and that you will have your attorney contact the Special Agent. You can fully cooperate through your attorney. This may sound paranoid, but the ramifications of getting flustered and running off at the mouth can be serious. Particularly given the fluid nature of who is a witness and who is a target, even statements you think sound innocent may not be.