Look at the methods for ItemManager in the API doc.   In particular the fetch methods.

very _sparse_ snippet:

         // workItem is a particular work item already fetched from repository
         IAuditableHandle auditableHandle = (IAuditableHandle) workItem.getItemHandle();
         IItemManager itemManager = repository().itemManager();
         ...
         handles = itemManager.fetchAllStateHandles( auditableHandle, null);
             List<IWorkItem> workItems = new ArrayList<IWorkItem>();
             
             workItems = itemManager.fetchCompleteStates(handles, null);

You can now iterate workItems and get the attributes you wish to examine, each of which is a historic view of the starting work item.