Ruth Jacks lived in Hohen Neuendorf near Berlin with her younger sister Esther and her parents. Her father Hermann was Jewish and her mother Elly had converted to Judaism on their marriage. They were forced to divorce in the spring of 1942. Elly Jacks and her daughters had to move out of the family home. They found an apartment in Berlin-Prenzlauer Berg. Ruth Jacks attended the Jewish school there until all Jewish schools were closed in June 1942. From September 1942, the 14-year-old performed forced labor in a uniform factory.
In March 1943, her father was deported to Auschwitz-Birkenau extermination camp. At around the same time, Ruth and Esther Jacks were also taken to the Große Hamburger Straße assembly camp. Their mother insisted they were “1st grade Mischlinge” (half-breeds). She succeeded in getting the girls out of the camp.
From then on, Elly Jacks and her daughters lived in constant fear of raids on their apartment. An acquaintance, Leo Lindenberg, let them stay in his garden house in Berlin-Wittenau. Esther Jacks died of diphtheria in the spring of 1945. Ruth and Elly Jacks survived in the Wittenau shed.
Ruth Jacks married Karl-Heinz Winkelmann in 1949.