After the First World War the German-speaking Thoeren emigrated to Germany where he became a theatre and film actor.
Thoeren appeared in leading roles in several German-language films made by Paramount at the Joinville Studios in Paris.
Thoeren had already ceased acting and begun writing screenplays for films and became a top writer in the United States working with leading directors including Joseph Losey and William Dieterle.
Thoeren returned to Germany after the Second World War and continued his career as a screenwriter.
[1] He married the German actress Erica Beer in 1957, but died in the same year in a car crash.