Born on June 26, 1916 in Bonn, Germany, Karlrobert Kreiten grew up in a musical family. His Dutch father, Theodor "Theo" Kreiten, was a composer, pianist, music professor and writer. His German mother was a classical singer, mezzo-soprano Emmy Liebergesell Kreiten, who performed under the stagename Emmy Kreiten-Barido. She was also a chamber singer. Karlrobert grew up in Düsseldorf along with his younger sister Annemarie.
Karlrobert showed incredible talent on the piano starting at a young age, making his public musical debut at the age of only 11, performing Mozart's 'Piano Concerto No. 23 in A major' in a live radio broadcast. In 1929 he was awarded a scholarship to study at the Music Academy in Cologne. He went on to win a number of prestigious piano awards, including the Silver Plaque of Honour at the International Music Competition in Vienna and the Great Mendelssohn Prize in Berlin, both in 1933.
Karlrobert trained under Jewish piano teacher Hedwig Rosenthal-Kanner in Vienna and then under the great Chilean pianist Claudio Arrau in Berlin, and by 1938 was performing concerts all over Germany and Europe with many favourably comparing him to Germany's greatest pianists. Some would later say he was on track to becoming Europe's greatest pianist of his time.
The spring of 1943 found Karlrobert, his sister and his grandmother, who were now living together in Berlin, in the process of moving from their small living quarters to a larger apartment. But Karlrobert was also needing to prepare for an upcoming concert tour, so an old aquaintance of his mother's, Ellen Ott-Monecke, offered him the use of her piano and music room. Assumably unknown to Karlrobert, Ellen was an ardent Nazi Party member and supporter, and when he voiced to her his negative opinions of Hitler, how he thought the war was already lost, and his disgust towards the ideology and repressiveness of the Nazi Party, she passed his remarks on to two of her friends who were also Nazi supporters and together they reported him to the Gestapo.