How might concentration camp doctors and guards have justified to themselves the death and suffering they caused other human beings?

fault-finding and looking to others that did the same to excise it

Explanation:

they were ordered to do it as a job, and that's how they had to see those people as one.

also, as money and food on the table, and if not they didn't eat.

also, they had to see people as objects and not merely human to be able to carry through the task at hand