Unable to remove domain users (from an old, migrated domain) still appearing in People Picker

Okay, so here is a complex scenario for everyone that I am really having difficulty with.

A domain migration occurred at the client site prior to my start at the client.

A migration from SharePoint 2007 to SharePoint 2010 also occurred, BUT the visual upgrade has not yet been applied to all existing 2007 content, and the customer refuses to do so at this time.

There are people appearing in the people picker from the previous domain for which we have already confirmed the following:

a) user has already been marked for deletion in the user information list when sql table was checked (with (nolock), of course).

b) user's account has been disabled in AD

c) stsadm.exe -o setproperty -propertyname "HideInactiveProfiles"-propertyvalue "true"has also been executed. 

d) searchadforest has been set to be only the current domain

e) user's profile has also been deleted. (confirmed by the error "User cannot be found" we receive when we do /_layouts/userdisp.aspx?ID=tp_ID that we receive when we try to go to the user's profile.

How in the world is the particular user's account still appearing in the PeoplePicker? Where is it coming from and how can we delete it?