I had the idea to do a story about a family in which crimes take place that basically go unpunished. Where, when and how in modern history could such facts take place? Only under Nazism. During the reign of Nazism slaughters and assassinations, whether mass or individual, were committed that were never punished. (…) I couldn’t create a glimmer of hope in this family of monsters, it couldn’t be done; it would have been like saying “we hope these monsters continue to live.” No, all of them had to be suffocated, locked in a gas chamber without any way out. While with the Valastro family [in La terra trema] and Rocco’s family there was always a glimmer of hope, here I had to end it hoping there was no hope, that there was no hope for these monsters; and, in fact, Götterdämmerung ends where the history of Nazism begins, and we all know what happened afterwards. (…)
The story of incest emerged slowly while writing the script, and it was the fruit of a dramatic narrative development that was anything but arbitrary. It is here that Martin becomes a true Nazi, in other words, nothing, no crime, stops him; the first family member Nazism chooses as its pawn is Kostantin, violent, loud, brutal but in the end unaware of the effects of the facts, and the next in line is Friederich, a technician, but who in the end in the eyes of the Nazis proves to be a coward in committing crimes (…) but claims to think with his own mind, so it prefers the final option, Martin: an absolutely reckless, degenerate boy, a worm, who has no moral problems, who does not distinguish between his little cousin and another little girl, and who becomes an instrument of Nazism without any will of his own.

Luchino Visconti, from Dialogo con l’autore, interview with Stefano Roncoroni, in Luchino Visconti, La caduta degli dei, edited by Stefano Roncoroni, Cappelli, Bologna 1969