He was seen by Wilhelm Furtwängler and others as one of the most talented young pianists in Germany. Born in Bonn, his German mother was the classical singer Emmy Kreiten, née Liebergesell, who sang under the stage name Emmy Kreiten-Barido. His Dutch father Theo Kreiten, was a composer, concert pianist, and writer. The Kreiten family originated in the area of the Lower Rhineland, along the current Dutch-German border.
Kreiten was reported to the Gestapo by Nazi neighbor Ellen Ott-Monecke about making negative remarks about Adolf Hitler and the war effort. He was indicted at the Volksgerichtshof, with Roland Freisler presiding, and condemned to death. Friends and family frantically tried to save his life, but to no avail. The family only accidentally learned that Karlrobert had been executed by hanging, with 185 other inmates, at Plötzensee prison.
His execution triggered a wave of articles in the German press about this "treacherous" artist. Prominent journalist Werner Höfer had to retire in 1987 when his articles about Kreiten became known to a wider public.
Today in Berlin, a memorial of the life and death of Kreiten exists along the "Topography of Terror" outdoor exhibit, which deals with the terror inflicted by the German SS and the Gestapo. The very prison cells that held him and others arrested by the Gestapo have been unearthed and remain laid bare for all to see. Streets in Düsseldorf, Bonn, and Cologne have been named in his honor. His only sister, Rosemarie von Studnitz, became a book publisher in the United States and died in 1975. In September 2003 the Dutch composer Rudi Martinus van Dijk had his work Kreitens Passion for baritone, full choir and symphony orchestra premiered in Düsseldorf by the Düsseldorf Symfoniker in memoriam of Karlrobert Kreiten.
- In Erinnerung an Karlrobert Kreiten (in German)