It's called a passenger manifest. Look into it. That's how they can notify next of kin within hours of a crash, or even less. After that, all you have to do is look at the manifest and see who didn't have next of kin asking about them, and who was on the list of non citizens who became suspects. It's simple police work, any junior grade detective, or for that matter, flat foot beat cop, would know how to do. It ain't rocket science.