Born the son of a judicial bailiff Dunckern grew up in Munich. After attending a grammar school he studied Law at the University of Munich, passing the First State Examination in 1930 and the Great State Examination in early 1933. When Himmler and his deputy Heydrich migrated from Munich to Berlin in April 1934 in order to take control of the Gestapo they took Dunckern along. In the following months he participated in reorganizing the Gestapo in accordance with the plans of the SS-leaders, thus decisively contributing to consolidating their power.