In order to apply for a passport, displaced persons could get the Vatican Refugee Organisation to write out a document identifying them. This is how many former Nazis were able to obtain passports to escape the country. Why was the Vatican Refugee Organisation allowed to write out identification documents? They were not allowed to; what they were doing was illegal.

Many refugees had no real identification documents left.

The Vatican had kept birth and death records for all prisoners.

This way, documents were from one source and not many countries.