 His first international productions included the historical drama "Napoleon", which Koch in appeared alongside Gérard Depardieu, John Malkovich and Isabella Rossellini and brought him more attention.He portrayed the youthful lover of Catherine Deneuve, Rodolphe Löwenstein, in "Marie und Freud".Koch has portrayed historically significant personalities, among Rudolf Höss in Costa-Gavras Hochhuth's adaptation "Amen (Der Stellvertreter)."