Determining if actual agent of work item is a substitute

[Ramki Maley]

Hello all,

Is it possible to determine if the actual agent of a work item is a 
substitute and not an original recipient (after work item is completed)  
and on whose behalf? I have been unsuccessful in my attempts to find 
this from the workflow tables. Making changes to the workflow is not an 
option at this time.

Regards,
Ramki Maley.