They need more to establish the fact that this is actually the person they claim to be.
This is way different for the bank teller that's known her for 30 years. They know who's standing in front of them (presumably).
Way different for someone that's never met this person. The bar is higher. These guys would would want more than just the one bank teller to affidavit that this actually is the person that all records show is actually deceased.
Depending on country and their bureaucracy (she does seem to be in France, so ...) this could be quite hard.