Born in Frankfurt, Germany, she lived most of her life in or near Amsterdam, Netherlands, having moved there with her family at the age of four and a half when the Nazis gained control over Germany. Born a German national, she lost her citizenship in 1941 and thus became stateless. By May 1940, the Franks were trapped in Amsterdam by the German occupation of the Netherlands. As persecutions of the Jewish population increased in July 1942, the Franks went into hiding in some concealed rooms behind a bookcase in the building where Anne's father, Otto Frank, worked. From then until the family's arrest by the Gestapo in August 1944, she kept a diary she had received as a birthday present, and wrote in it regularly. Following their arrest, the Franks were transported to concentration camps. In October or November 1944, Anne and her sister, Margot, were transferred from Auschwitz to Bergen-Belsen concentration camp, where they died (probably of typhus) a few months later. They were originally estimated by the Red Cross to have died in March, with Dutch authorities setting 31 March as their official date of death, but research by the Anne Frank House in 2015 suggests it is more likely that they died in February.