Salomon and Perla Krieser left Poland and immigrated to Germany after their wedding in 1920, and then moved to Antwerp. Salomon owned a factory for the manufacture of women's clothes. When the bombing of Belgium began in 1940, Perla and Salomon escaped with their two daughters, 16-year-old Hilda and 12-year-old Hannah, and crossed over into France. Making their way southward, they were arrested along with many other refugees and sent to the Riversaltes camp.
During their time at the camp, Hilda worked as a kindergarten teacher for the Secours Suisse aux Enfants, an organization founded by Maurice Dubois on the outbreak of World War II in order to treat child refugees in Toulouse, France. By 1940, the Secours Suisse operated under the auspices of the Swiss Red Cross. In exchange for her work, Hilda received extra food rations that she shared with her parents and sister. Eventually, Hilda and Hannah were sent out of the camp to work at a Red Cross children's home in Pringy, on the Swiss border. Armed with false papers, the sisters hid their Jewish identity from the children they worked with. Meanwhile, they kept in touch by letter with their parents in Riversaltes.
In late August 1942 policemen brought the girls back to Riversaltes, ostensibly to reunite them with their parents and move the family to a new camp. While the sisters waited to board the deportation train, Friedel Bohny-Reiter, a member of the Secours Suisse, succeeded in removing them from the line and hiding them in a warehouse together with other children. With the assistance of a municipal bureaucrat who forged an ID card for Hilda, she obtained permits for them to continue working in Pringy.
Until August 1942 the sisters managed to maintain a correspondence with their parents through letters and postcards, writing in Hebrew in order to circumvent the censorship laws. They wrote to them of their health and how they passed their days in the children's home. Their mother Perla wrote them words of encouragement and love. In one letter, she told them not to fast on Yom Kippur for health reasons, and to dedicate the day to prayer. Perla was eventually sent from Riversaltes to the Drancy transit camp, and then deported to Auschwitz-Birkenau. She threw her last postcard to her daughters from the deportation train.
Salomon was assigned to the labor battalions of the Groupe de Travailleurs Etrangers (foreign citizens under the Vichy regime). He attempted to escape but was caught and sent to Auschwitz-Birkenau on Transport 29. A short time before his deportation, he succeeded in sending his daughters a package, containing his tallit (prayer shawl) with which he prayed each day, a little money and a postcard written in Hebrew. It was the last postcard they received from him. On it, he wrote: "If we survive, we will meet up in Belgium".
Salomon and Perla Krieser were both murdered in Auschwitz-Birkenau.
Hilda and Hannah remained in Pringy until the war was over. Friedel Bohny-Reiter was later recognized by Yad Vashem as Righteous Among the Nations.