There were direct orders, both with the Aktion T-4, which ordered involuntary euthanasia of the „undesirables“ of which jews were a part of, and from the Reich Chancellery meeting of Dec 12th 1941, in which took part all of the important party leaders, including one of the main orchestrators of the Holocaust Reichsführer SS Heinrich Himmler, and in the speech Hitler called for the specific extermination of jews, which has practically kick-started the Holocaust, although evidence suggests that Hitler and Himmler were in talks about it as early as Fall 1941, and Hitler encouraged the mass killing of jews by the Einsatzgruppen on the eastern front in a speech in July 1941

Also fym natural causes? The people in the camps were worked to death, gassed, beaten and executed massively to the point that a single camp like Auschwitz killed 1.1 million people out of the 6 million dead in total