Eduard Nierscher worked from 1927 to 1935 at Galerie Harding, Kärntnerstraße 16 in Vienna’s 1st district. It was there that he met his future wife Anna Schatz, who worked as a housemaid for the mother of the Harding brothers. In 1935 he left the gallery to become a self-employed art dealer in the basement of Bäckenbrünnlgasse 5 in the 18th district. After the annexation of Austria to the German Reich in 1938, he moved into the apartment of the Jewish sewing machine agent Osias Rosenkranz at Bäckenbrünnlgasse 5 and also took over his interior furnishings without payment. Rosenkranz was deported in 1941 to Litzmannstadt (Łódź) and later murdered. Nierscher dealt above all in pictures in line with the aesthetic preferences of the Nazi elite, such as those by Karl Feiertag, Franz Waldegg, Gustav Prucha and Leopold Rothaug. He tried insistently to gain title to Galerie Harding at Kärntnerstraße 16 but was unsuccessful, because the Property Transactions Office had approved the takeover in 1939 by Helene Silverio, an “Aryan” employee of the business. Nierscher nevertheless managed to acquire the branch in the Bohemian spa Marienbad (Mariánské Lázně) without payment or consultation with the authorities in the Protectorate of Bohemia and Moravia responsible for “Aryanization”. He continued his unsuccessful attack on the Vienna office and put Arnold Harding, co-founder of the gallery and persecuted as a Jew, under extreme pressure. He used his knowledge that the two had been engaged since before 1938 to threaten Harding with internment in a concentration camp and Silverio with arrest by the Gestapo. According to the Regulation against Helping to Disguise Jewish Businesses of 22 April 1938, persons “who helped to disguise the Jewish nature of a business” were liable to heavy fines or imprisonment. Moreover, relationships such as those between Silverio and Harding were subject to severe punishment as “racial defilement”. Nierscher was called up to the Wehrmacht in 1941. He was captured as a prisoner-of-war and did not return to Vienna until September 1945.

After the war, the Czech authorities seized the branch of Galerie Harding in Marienbad “Aryanized” by Nierscher. In 1948 the Volksgericht in Vienna instigated proceedings against Nierscher under sections 8 (Registration fraud and illegality) and 10 (Denunciation) of the War Criminals Act. The accusation of denunciation referred to a report to the Gestapo by him in August 1940 concerning the disguised business takeover and the intimate relationship between Silverio and Harding. As the court only had a copy and not the original letter, Nierscher was given the benefit of the doubt and acquitted for lack of strict evidence. The court also acquitted Nierscher of the other offences, because his claim not to have applied for membership of the NSDAP until 1939 on the occasion of a trip to Switzerland could not be disproved.