What if Europol claims it holds no data on me but I believe this is incorrect?

A ‘no data held’ response is not always accurate. Europol may issue this response where data exists but is classified at a level that prevents acknowledgment, or where data is held under a different spelling or alias. You can challenge a suspected false negative by filing a complaint with the European Data Protection Supervisor, who has authority to conduct an independent verification. The EDPS can access Europol’s systems directly and confirm whether data exists without revealing classified content. This mechanism is particularly important where you have concrete reasons — such as a related Interpol notice or extradition request — to suspect data does exist.