My aunt passed away. She wasn't married and had no children. She had planned to leave her house to me. The notary with whom she had deposited her will, told me that she had taken it back. How do I know that they’re telling the truth?

When a notary is entrusted with a will, it is registered in the central register of last wills and testaments, unless the testator objects (Art. 4.1.b of the Basel Convention of May 16, 1972, on the Establishment of a Scheme of Registration of Wills). If the will has been registered and the testator has requested its return from the notary, this information will also be recorded (Art. 4.2 of the same Convention).