Workflow :: How To Find Actual Responder Name Displayed In Notification

Where are the details of the Actual Responder Details stored in the case of the below scenario

If a notification for one user was closed by another user through access to the first user's worklist, the name of the second user, who actually took the action, is displayed as the responder.

I am only able to find the Original Recipeint username in the wf_notifications table.But where will the details of the Actual Responder name displayed in the notification be stored.

When I use the "wf_notification.Responder" function, I get the Original Recipeint username of the user but not the one who acted on the notification. Is there ANY way by which I can get the Actual responder user name who acted on the notification

select responder from wf_notifications where notification_id = <nid> also gives me the Original Recipeint username of the user but not the one who acted on the notification