Thekla Heilbrun, née Rosenau came from a long-established Jewish family of Bad Kissingen whose roots can be traced back to the 18^th century. She was born in Bad Kissingen on February 22, 1877 as the second child of the respected jeweller Simon Rosenau and his wife Henriette, née Rosenberg.

Her father had an excellent reputation as a jeweller, a gold and silver worker as well as a court antiquarian of the Bavarian King and often received international awards for his gold and silver works. It was also Simon Rosenau who manufactured the office chain of Bad Kissingen’s Mayor in 1907. In addition, he was also very active in the Jewish Community, e.g. as the head of many years of the Israelite Cultural Community. 

In January 1900 Thekla Rosenau married the banker Otto Heilbrun, who was born in Eisleben, and lived in Erfurt with him. Otto Heilbrun ran a banking business there. Their daughter Hildegard was born in September 1900 and their son Werner two years later in 1902.

Thekla and her husband moved to Wiesbaden in the mid-1920s. The family was able to emigrate in time. In July 1938, Thekla and her husband travelled to the United States to visit their daughter who had got married in the meantime. Then they obviously emigrated to England in 1939 and lived in Willesden in north-west London until 1942. 

In October 1942 they emigrated to the United States and settled in Davenport, Iowa, where their daughter and son-in-law lived. Shortly after their arrival, the Davenport newspaper "Daily Times" wrote: "Mr and Mrs Otto Heilbrun, most recently I[nhabitants] of London and formerly of Erfurt and Wiesbaden, Germany, enjoyed the best night's sleep last night in four years. They slept without fear of whistling bombs, or the probings of an evil gestapo. They arrived Tuesday from New York, where they landed less than a week ago from London, to make their home from now on with their daughter and son-in-law, Dr. and Mrs Ralph A. Anrode, 2505 LeClaire street, Davenport." (Daily Times, Davenport, 04.11.1942). But they were meant to live there for only a short span of their lives. In 1943, Otto Heilbrun died and Thekla died only one year later in March 1944. Both of them are buried on Mount Nebo Hebrew Cemetery there.

Thekla's son Werner studied medicine in Freiburg, Munich, Berlin and Heidelberg and finished a doctorate in Heidelberg in 1927.  He then practiced as a doctor in Berlin-Köpenick and worked as a psychotherapist and assistant doctor in the sanatorium and nursing home in Berlin-Buch (northern part of Pankow) from 1930. He also took over the psychotherapeutic treatment of children in the children's home or remedial education home for difficult-to-educate boys and girls from Annemarie Wolff-Richter.

Like many of his Jewish colleagues, he was dismissed from the Health Services on the basis of the “Gesetz zur Wiederherstellung des Berufsbeamtentums“ (Law to Restore the Professional Civil Service) passed on April 7, 1933. He first emigrated to France and then to Madrid with his wife Almuth. After the outbreak of the Spanish Civil War, the couple made themselves available to the Red Aid and took care of a hospital in Madrid and 400 children in a children's home. Later Werner Heilbrun fought against Franco's troops in the Spanish Civil War as a member of the XIIth International Brigade. Because of his medical training, he was appointed Chief Physician of the XIIth Brigade. He was killed on June 12, 1937 during fights at the foot of the Pyrenees after being hit by a machine gun volley from an airplane. Werner Heilbrun was a close friend of the authors Ernest Hemingway and Gustav Regler. After Heilbrun's death, Hemingway instructed his publisher to pay the license fees for his screenplay, "The Spanish Earth", filmed by Luis Buñuel, to Heilbrun’s widow. The author Gustav Regler, who was also a friend of Hemingway and who worked as a "Political Commissioner" in the XIIth International Brigade together with Heilbrun, immortalized his friend Werner Heilbrun in his novel "The Great Crusade" published in 1940 in the character of Werner, the doctor of the brigade.