In 2018 and 2019, Chicago’s Leslie Hindman Auctioneers sold two paintings to New York City’s Hirschl & Adler Galleries, which were alleged Henkel fakes. The works were supposed to be by Precisionism artist George Copeland Ault, and cost the gallery $709,000.
Henkel and his operation have also been linked to two works by Precisionist Ralston Crawford, one by Surrealist Gertrude Abercrombie, and three more Ault paintings. In May 2016, Henkel sold a Crawford painting titled Smith Silo at Leslie Hindman Auctioneers for $395,000. The painting is now considered a forgery.