Karoline (Lilly) Nehammer, née Prinz, was one of the most important figures in the art market in Nazi Vienna. Her business activities were closely linked with those of her brother Rudolf Prinz and her business partner Oskar Hamel. Her sister Rosa Golwig was also an art dealer. After the death of her husband (Heinrich Nehammer) in 1927, she took over his business in 1928, an antiques dealership at Bellariastraße 6 in Vienna's 1st district. In 1931 she moved the business to her home address, Piaristengasse 11 in the 8th district. After the Chamber of Industry and Commerce decreed that the business was more than a small business, it was entered in the register of companies with the addition "Alte Kunst". In 1942 Karoline Nehammer and Oskar Hamel purchased Burg Seebenstein in Pittental near Wiener Neustadt from the ruling prince Franz Josef II von und zu Liechtenstein for 115,000 Reichsmarks, most of which was paid, according to the buyers, in the form of art objects. The castle, as Nehammer and Hamel later pointed out in the Volksgericht trial, became a meeting place for prominent members of the Vienna art and culture scene, including Richard Ernst, director of the Staatliches Kunstgewerbemuseum (State Arts and Crafts Museum), and Herbert Seiberl, who headed the monuments authority during the Nazi era. In 1943 Hamel and Nehammer moved most of their stock to the castle, allegedly to protect it from air raids, and bricked it up. They claimed to have transferred other items together with Rudolf Prinz to Ernstbrunn in the Weinviertel.

At the instigation of the Department for Securing Property in the State Office for Internal Affairs, criminal proceedings were initiated against Karoline Nehammer, Rudolf Prinz and Oskar Hamel by the Volksgericht for unlawful enrichment (Section 6 of the War Criminals Act). They were accused in the brief submitted to the public prosecutor's office of purchasing art objects belonging to persecuted Jews at giveaway prices and then reselling them at great profit. The Bundesministerium für Vermögenssicherung und Wirtschaftsplanung (Federal Ministry for Securing Property and Economic Planning) established in autumn 1945 spoke of enormous profit margins. Many of Nehammer and Hamel's earlier guests at Burg Seebenstein spoke in their defence. The case against Nehammer, Hamel and Prinz was discontinued in 1946. The expert opinion of Hermann Reuther, director of the Wiener Städtische Sammlungen from 1924 to 1936, played an important role. During the Nazi era he had been an art expert in the Dorotheum and had also been invited to Seebenstein. In 1967 Nehammer gave up her business permit and liquidated the company, which was deleted from the register of companies in 1968. Provenance research in museums is hampered by the fact that there are no details in Karoline Nehammer's purchases regarding the former owners.