His crimes were not morally right and his entire followers were punished, but he got his view out there as morally right in Germany.
Mill's is in no way similar to Hitler, but I referenced how their outlooks are expressed in some form. Mills view factored in the many things that affect Utilitarianism from pleasures, consciences, and down to moral standards. "Of two pleasures, if there be one to which all or almost all who experience of both give a decided performance, irrespective of any feeling of moral obligation to prefer it, that is the more desirable pleasure" (Utilitarianism. Pg.8). Summing it up, one can do what is morally right for themselves based on the feeling it gives them regardless of good or bad. It shows moral standards are formed more based on the appetite of the pleasure than its ethics.
The conscience is defined as the consciousness of the moral right and wrong of one's own acts or motives. Mill's carried on this subject about conscience, "But is utility the only creed which is able to furnish us with excuses for evil-doing and means of cheating our own conscience?" (Utilitarianism. Pg.25). That gives insight on how Hitler executed his plan of killing millions and with no remorse, perhaps using utility as though it was necessary to kill the Jews for Germany's well-being and thus lying to his morals and conscience. .
He then went into the moral standards and how it all comes into work together. The moral standard is set in a society and a person has to adopt it. The person ways options out to accept it and decide for themselves. "He says to himself, I feel that I am bound not to rob or murder, betray or deceive; but why am I bound to promote the general happiness? If my own happiness lies in something else, why may I not give that the preference?" (Utilitarianism. Pg.27). This plays heavily on a person's pleasures and conscience to do what is morally right and yet get a good feeling pleasure from it.