Yad Vashem has a testimony by Dr Fritz Kassel, his cousin, giving Leonhard's birth as about 1892 in Ratibor, and two entries for a person of the same name deported from Berlin (where Dr Kassel says they lived before the war) on 06/03/1943, born in Gostyn on 30/01/1893. The latter is used here as there is a similar entry for his brother Rudolf.