The same issue already exists in more limited form with fingerprints. Often random prints are found near the scene of a crime. That's not proof, however--just

The same issue already exists in more limited form with fingerprints. Often random prints are found near the scene of a crime. That's not proof, however--just cause for questioning. If the police didn't question potential suspects they wouldn't be very good at their job, but I'm sorry it freaked you out.