Hello Jishin,
according to the death certificate, your great grandfather was living in Lüneburg, just 1 hour driving distance from my home.
My grandfather was a Nazi. Not directly involved with the deportations, but he supported the whole monstrousness.
The friendly old granddad, we often visited, partially turned into a monster, as I learned about the Nazi atrocities.
Quite a lesson for a young child.
Gassho,
Kotei sat/lah today.