It would seem equally likely that your original client was the entity that performed the white labeling. In which case they white labeled the site, and sold that cleaned product to AJ. In that scenario, AJ never saw a copyright, and your client is not only responsible for the issue, but also for distribution of copyrighted material for profit, which may not be in the best interest of your business. You have not mentioned any communication with the original client, which I doubt is the case, but I would tread lightly as the Dutch seem to be pushing for criminal pirated resale guidance from the EU, unless you are comfortable with that escalation.