Error Message: Resources have items checked out to them and could not be deleted.

A resource left my company but I can't delete him from PWA with this warning message "Resources have items checked out to them and could not be deleted".

I went to force check-in area, I couldn't find him there either. I also queried the entire database, he isn't there either. What is the next step? I hate to just leave him in the PWA, if he is no longer with us.

Thank you,