JRI-Poland records the death of Hirschel Katz in Langendorf on 27/10/1820 aged 65 years, implying he was born in 1755-56.

Sonja Delander in the Nothmann Chronicle names him as Hirsch (page 3) and says he died in 1821 (page 14, citing Friedrich Nothmann's manuscript).

Friedrich Nothmann in Geschichte Notthmann (page 102) mentions "Z'vi oder Hirschel Katz" who died in 1821 as one of the four sons of Jehuda Ha-Kohen and says he saw the four brothers' gravestones in Langendorf in 1936. The four brothers were obliged to adopt different surnames: the Hebrew roots of the surnames adopted by Joel and Jacob Hirschel are identical: Cohn equates to kohen (priest) while Katz is a contraction of the paternal title kohen zedek (righteous priest).

Mike Liebermann states "Jacob (Hirshel) KATZ was born in 1745 in Zuelz, and died on 7 Mar 1821 in Langendorf" implying he died aged 75-76 years. Liebermann is the only source I have found to use the name Jacob in addition to Hirsch/Hirschel or its Hebrew cognate Z'wi.

The Katz line is hard to follow; the name appears in the locality in subsequent generations, but without definitive links to previous generations. The most likely heir to the family is Hirschel Loebel Katz who lived in Langendorf and whose names follow those of his putative grandfather and father.

Records of moves identify Hirschel Loebel Katz as the father of Loebel Katz al[ias] Cohn, and of Abraham Katz. A note in the movement register against Abraham Katz says that he was not mentioned in the family register, nor was his birth registered. The fact that Loebel was using the alias Cohn rather than his father's surname of Katz, and that Abraham was not registered under the name Katz, may explain the difficulty in following the Katz name through Hirschel's descendants.