Marsen works as a moderator and reporter mainly for the BR editorial offices Politics and Background and radioWissen. He is also a regular author of documentation and features. His main topics include historical National Socialism and the current extreme right-wing scene. For example, he reported on the trial against the terrorist group NSU for the ARD for five years. He has received several awards for his journalistic work, including the gold medal at the New York Radio Festival, the Wilhelm vo