She was born on June 1, 1906 and grew up as the second of the five children of the dealer’s family of Abraham Michel and Minna, née Widawski in Edelfingen and Würzburg. Her father was a bookbinder. Hanni attended the school in Würzburg’s Ursulinenkloster (monastery of the Ursulines) and then apprenticed as a hairdresser. In 1923, she first went to the Middle Franconian town of Fürth and worked there and then in Würzburg, Bad Kissingen, Bremen and Hamburg in her profession. 

From October 1927, the young hairdresser stayed in the Lower Franconian spa town of Bad Kissingen. Her employer was Fritz Reußenzehn who owned a hairdressing salon together with a massage and chiropody practice in Kirchgasse. As early as in May 1928 the still unmarried Hanni moved on to Leipzig.

In 1929 she moved to Ochsenfurt where she soon got to know Stefan Sieber and married him in 1931. Stefan Sieber, who worked as a mechanic (fitter), was a Catholic. Because of that the couple got married according to the Catholic rite. In 1933 or maybe in 1935, Johanna officially converted to Catholicism (contradictory statements in the sources). She kept on working as a hairdresser’s assistant in Ochsenfurt until her life took a fateful turn in December 1938.

Gestapo (secret state police) in Würzburg started investigations against her and a non-Jewish acquaintance of her because of a sexual relationship between them. This violation of the “Nürnberger Rassegesetze” (Nuremberg Race Laws) was branded as “Rassenschande” (racial disgrace) by the Nazi authorities and relentlessly punished. The minutes of her interrogation show how ruthlessly and degradingly the police forces, Gestapo and judiciary of the Nazi government meddled with the privacy of the people in order to push through their racial ideology. After his interrogation in Ochsenfurt District Court Prison, the indicted acquaintance was taken into investigative custody by the “Große Strafkammer” (large criminal chamber) of Würzburg District Court because of “Rassenschande” and sentenced to imprisonment of one year and five months in May 1939. The heavily pregnant Johanna Sieber was initially spared imprisonment. She gave birth to her child on December 6, 1938. In March 1939, her husband Stefan applied for being handed out a passport for himself and his wife. The family hoped to be able to emigrate to Canada. But the authorities approved of only a passport for Stefan Sieber and stated it was not possible for his wife “before the criminal proceedings because of racial disgrace weren’t concluded”. Eventually, the Gestapo ordered for her to be taken into “Schutzhaft” (protective custody). On account of her imminent emigration an internment in a concentration camp would be dispensed with”. Johanna Sieber was imprisoned in Ochsenfurt District Court Jail since June 1939. The reason why her emigration plans couldn’t be realized can’t be found in the files.

Johanna Sieber was murdered in the killing facility of Bernburg on April 14, 1942. Presumably that happened as part of the action 14f13 meant for the “special treatment” of Concentration camp inmates who were no longer able to work. The true circumstances of her death were kept secret to the surviving members of her family. The news of her death released to her husband gave as the reason for her death “heart failure caused by cell tissue inflammation of her left lower leg and thigh”. 

Johanna’s mother and her brother Heinrich were deported from Würzburg to Riga in November 1941. Her brother Jacob who had emigrated to Palestine dedicated memorial sheets in the National Memorial Yad Vashem to them.