First, you can't produce what you don't have.  If you know where copies are (like filed with a probate court, or with an attorney that handled the probate), you may want to advise the grand jury of where they can get the requested documents.  Second, as far as indicting you... it will depend on the evidence presented to the grand jury.  If they feel they have enough evidence to move forward, then yes they can indict you -- even if many of the documents have been lost or shredded.  If you are not sure about how to respond to a question or a request for certain records, you should consult with a criminal defense attorney in your area.  Many will charge a nominal fee for a consultation relating to a grand jury sub-- getting help at this point to fight the charges is easier than trying to fight them after indictment.