Catharina Groen was a daughter of Eliazer Groen and Rosina de Haan. In the Groen family eight children have been born, of whom only the eldest son has survived the Holocaust. Catharina married (presumably about 1940 in Den Haag) to Karel Louis Leons, a son of Salomon Leons and Dina Selina Wolf. He was previously married to Elise Philips van Buren but divorced from her in March 1939. Catharina Groen has been sent from transit camp Westerbork to Auschwitz on 18 September where she upon arrival there on 21 September 1942 has been killed immediately. Her husband was deported the same 18 September 1942 to Auschwitz where he eventually lost his life on 31 December 1942.
Municipal Archive of Den Haag, City Archive of Rotterdam, City Archive of Amsterdam, archive card of Elise Philips van Buren, the file cabinet of the Jewish Council of Amsterdam, records of Catharina Leons-Groen and Karel Louis Leons.