You should consult with an attorney in your are on this matter.  The use of subpoena's differs from state to state but generally speaking, they are a very strong instrument and may not be used lightly.  Some states do not allow even attorneys to issue subpoena's anymore because of the fear that they instill.  Also, banks and other financial institutions may not honor a subpoena unless they are "court ordered" or in other words, issued and signed by a Judge.  Collecting on a judgement from a debtor that is not physically in your state or has assets in a state can be very tricky.  If the judgement is substantial enough then you may want to consider speaking with a professional agency that collects debt.  Good luck.