Criminals don't actually don't belong in a concentration camp. That they still form a permanent category in all camps is, from the viewpoint of the totalitarian power apparatus, a kind of concession to the prejudices of society, which in this way can be made to get used to their existence the most easily."Elemente und Ursprünge totaler Herrschaft", S. 657
Behind the blind bestiality of the SA, there often lay a deep hatred and resentment against all those who were socially, intellectually, or physically better off than themselves, and who now, as if in fulfillment of their wildest dreams, were in their power. This resentment, which never died out entirely in the camps, strikes us as a last remnant of humanly understandable feeling. The real horror began, however, when the SS took over the administration of the camps. The old spontaneous bestiality gave way to an absolutely cold and systematic destruction of human bodies, calculated to destroy human dignity; death was avoided or postponed indefinitely. The camps were no longer amusement parks for beasts in human form, that is, for men who really belonged in mental institutions and prisons; the reverse became true: they were turned into "drill grounds," on which perfectly normal men were trained to be full-fledged members of the SS."The Origins of Totalitarianism"
Compared with the insane world of the concentration camp society itself, which can never be quite grasped by the imagination, because it is outside of life and death, the process by which humans get prepared and [zugerichtet] for it, is rational and purposeful. The [Anstoß], and what's more, the tacit approval of such conditions in the middle of Europe, was created by those events, which in a period of dissolving political forms suddenly had suddenly made hundreds of thousands and then millions of people homeless, stateless, rightless, economically superfluous and socially unwanted. On them it already had been demonstrated that human rights, which were never philosophically founded nor secured politically anyway, had lost even their proclamatory, their appelatory effect and were at least in their traditional form no longer applied anywhere. But these are only the negative preconditions; after all the loss of the workplace and therefore the place in society, which came with unemployment, or in the case of statelessness the loss of papers, home, a secure place to stay and a right to work, were only preliminary, summary preparation, which would have hardly sufficed for the ultimate result.
Regardless, the first crucial step on the way to totalitarian power is the killing of the juridical person, which in the case of statelessness happens automatically because the stateless person ends up outside of all law. In the case of totalitarian power this automatic killing becomes a planned murder, because concentration camps are always placed outside of the penal system, and the inmates are never to be put there "for punishable or other offenses" (also see Maunz, p. 50). Under all conditions totalitatarian power takes care to put people into the camps, which only *are* -- Jews, carriers of diseases, members of dying classes -- but have already lost their ability to act, be it for good or bad."Elemente und Ursprünge totaler Herrschaft", S. 655
To the amalgamation of politicals and criminals, with which the concentration camps began both in Germany and Russia, soon a third element is added, which would soon form the majority of all inmates. This largest group consisted of people who hadn't done anything that stood in any rational relation to their imprisonment, be it in their own mind or in that of their torturers. Without them the camps could have have existed, that is, they would not have survived the first years of the regime.
These in every sense innocent people do not just form the majority of all the camp population, they also are those, which finally were "exterminated" in German gas chambers. Only on them could the murder of the juridical person be performed so completely that they could be "processed", without names, deeds or misdeeds, by which they could have been recognized, in the mass factories of death, which just because of their sheer capacity could not take individual cases into account anymore. (A Jew for example, who had done a "crime" against the Nazi regime, didn't even get put in there in the first place, they were shot or beaten to death right away.) From the beginning the gas chambers were not intended as means to intimidate or punish; they were intended for Jews or Gypsies or Poles "in general", and they served to prove, that humans in general are superfluous.
While the separation of inmates into categories was merely a tactical-organisatory measure for the the purpose of administration of the camps, the arbitrariness of committal demonstrates the essential principle of the institution as such. The existance of a political opposition is just a pretext for the concentration camp system, and its purpose is not achieved when the population more or less voluntarily conforms as consequence of the most monstrous deterrence, that is, to give up its political rights. The arbitrariness has the purpose to deprive those under the totalitarian regime of all their rights as citizens, which finally become as outlawed [vogelfrei] in their own country as otherwise only the stateless and homeless. The deprivation of humans of their rights, the killing of the juridical person in them is just a precondition of their being totally controlled, for which even voluntary agreement is a hindrance. *[Related to that is the fact that all propaganda and ["Weltanschauungslehre"] was expressly forbidden in the camps. (also see Himmler, "Wesen und Aufgabe der SS und der Polizei"). And together with this in turn it has to be considered that that teaching and propaganda was also not allowed for the guarding elite formations; their Weltanschauung was not to be "teached", but "exercized" (see Robert Ley)]*. And this is not just the case for special categories of criminals, political enemies, Jews, on which it was tested [first], but for every citizen of a totalitarian country."Elemente und Ursprünge totaler Herrschaft", S. 658 ff.
The concentration camps, by making death itself anonymous (making it impossible to find out whether a prisoner is dead or alive), robbed death of its meaning as the end of a fulfilled life. In a sense they took away the individual’s own death, proving that henceforth nothing belonged to him and he belonged to no one. His death merely set a seal on the fact that he had never existed."The Origins of Totalitarianism"
Still the element of criminals must not be missing from any concentration camp. [..] the fact that nearly without exception they compromise the aristocracy of the camps and fulfill administrative duties, shows clearly that it is much harder to kill the juridical person of a human who is guilty of someone, than of someone who is innocent. The rise of criminals into the aristocracy of the camps is similar to the improvement that happens in the juridical situation of the stateless, who also lost their rights as citizens, when they resolve to commit a theft."Elemente und Ursprünge totaler Herrschaft", S. 656