Your observation, again, is reasonable and does reflect the process that has been in place here in Canada for many years. I can tell you from experience with respect to efforts undertaken by a number of different governments here in Canada to establish the status of alleged Nazi war criminals that the governments had to produce substantial information—and sometimes were unable to and were therefore frustrated in undertaking proceedings—to establish that they weren't stateless, that they were nationals of another country as well.
It's hard for me to contemplate circumstances in which a government or a minister would undertake action absent of clear documentation, which the minister would have, that would indicate that the individual in question did have status of citizenship in another country.