First, figure out the UserID.
In my example, I'm looking up the UserID for the login ban
Select * From [Davidw3_PortalFX].[dbo].[PWUser]
Now, look up the SID connected to the UserID
Select * From [Davidw3_PortalFX].[dbo].[PwWindowsUserMapping]
Once we have the SID, we can look it up in the active directory and see if they match. The SID is in hexadecimal