Custom Report

I am generating some Custom ASP.NET pages which act as a report for me in my Smart Form Application. I am able to get users Worklist and display the datafields i require. I am also able to open an Active Process and display required DataFields using the FilterService Webservices.

Can someone suggest a way to get the datafields of the Processes which are already Complete. Is there any webservice or method to achieve it???

Or any custom work around to do that.
its a little Urgent

Thanks in advance
Awwab