The only things I have is that he came from Tarnów. And at that time belongs to Austria.
When he travelled to his country again, because he work in order to bring polish families to Brazil, he had a document with the nazi seal giving him the authorization for his travel. In this document, the name was Eugenio Bendaszeski, and Olga Bendaszeski, his wife.
We don't have birth documents, or something like that.
In the books, the surname appear as Bendaszweski.
Lookink in the Mormon site, appear that he was an austrian, and the names of his parents Joze and Carolina.