There's actually an amazing book on this that details the missions of Reserve Police Battalion 101 titled "Ordinary Men" by Christopher Browning. In it browning describes how this group of men who were all 30-50 years of age were able to commit a host of atrocities against the Jewish community in Poland. At first it was very difficult for these men and they were given the opportunity to not take part in the killing. Many of the soldiers actively tried to avoid taking part in the mission, but with the after this first morbid mission many more started being ordered. By their fourth mission these men went on they had already become numb to the task of killing Jews. Anywho, you should really read the book, because it is absolutely fantastic and makes you rethink what you knew.

While not related to history, you may also want to take a look at "The Lucifer Effect" by Phillip Zimbardo, either that or chapter 11 of "Psychology -core concept", same author. Those are a book about social psychology. They will answer your second question: - how to get people into a mind state where they were comfortable doing that kind of thing.

I highly recommend reading, " Into that Darkness by Gitta Sereny". It is based on extensive interviews, an unprecedented potrait of Franz Stangl, Commandant of Treblinka-the largest of the the five Nazi extermination camps. (Word for word as it says on the front cover)

Puh... This is a huge question (and a very interesting one, seriously, you really have a knack for asking highly interesting questions).

As for the first part of the question: It is not exaggerated. By all accounts, the Concentration Camp SS had a higher potential for violence that other groups. Karin Orth in her book Die Konzentrationslager-SS. Sozialstrukturelle Analysen und biographische Studien. [The Concentration Camp SS. Social-structural Analysis and biographical studies] finds that within the Camp SS a higher percentage of convinced perpetrators can be found than in the comparable study of the police battalion by Browning. While Browning points out that 20% of the unit he researched can be seen as people murdering Jews because they are convinced anti-Semites while 60% took part because of the element of social pressure, Orth finds that the percentage of the convinced and ideological perpetrators were higher among the Concentration Camp SS.

Similarly, the camps were an environment that incentivized violence. Something surviving prisoners of the camp describe in great detail is that guards would take their caps and throw them outside of the guard cordon. They then told the prisoners to go get their cap. If the prisoner went, they shot them in the back and claimed, they were shot while attempting to escape. If they refused, they were shot for refusing an order. The reason why this particularly perfidious method is so present in almost all survivor narratives is that a guard shooting a prisoner attempting to escape could get three to five days off of work. The camp administration of course knew about this practice since it was basically invented in Dachau in 1933/34 and a lot of later camp commanders had started out there. Basically, this system of rewarding wanton violence and murder among the Camp guards lead to a highly violent and dangerous atmosphere in the camps.

And it brings us right to the second part of the question about why the perpetrators became perpetrators / how they were formed into killers. This is one of the questions historians have tried to answer in various ways basically since research into the subject of camps and the Holocaust began. The historian Peter Longerich in one of his articles talks about the various factors we can identify in answering this questions. In the framework of the question about Concentration Camp Personnel, the relevant factors he discusses in broad terms are disposition, situation, ideology, and utilitarian motives.

Disposition and situation as well as ideological and utilitarian motives are often juxtaposed or discussed in as dichotomies. Longerich rejects that way of framing the debate, arguing that it is imperative to see them more in a dialectic framework, i.e. producing a synthesis of both and thus creating a complex layer of motivations and background for why Nazi perpetrators acted the way they did.

Disposition in this framework means how susceptible past experiences with violence and violent ideologies perpetrators were to exact violence against prisoners or civilians. Several studies about perpetrators have revealed that a lot of later high ranking Nazis for example had been part of the Freikorps after WWI, something which Orth also finds relevant concerning the older members of the Concentration Camp SS. The Freikorps as radical right-wing paramilitary groups fighting in the Baltic and around other areas of Germany's former borders after WWI espoused a radical anti-Democratic and anti-Bolshevist rhetoric and ideology as well as glorify violent action and being uncompromising with one's enemies. Playing also an important role in internal post-WWI German politics such as with the murder of Rosa Luxemburg and Karl Liebknecht, the violent overthrow of the Munich Soviet Republic and the murder of Walter Rathenau, the Freikorps can be seen as a fertile breeding ground for later Nazis. Of course, there are other experiences one can summarize under disposition but this is in my opinion the most powerful and pertinent example.

Situation in Longerich's framework refers with regard to the camp personnel to the situation and atmosphere within the camps. Camp Administrations created a situation in which violence against prisoners was legitimized by presenting them as a (sometimes existential) threat, incentivized violence and through institutional means created a framework for individual actors under which violence against prisoners was normalized and seen as necessary and natural. Simply put, a lot of the violence and murder exacted against prisoners stemmed from said violence being perceived as normal and expected. This ties into Browning's argument about social pressure with the important difference that while Browning focuses on the group dynamics within a police unit, an institution such as a concentration camp was even more powerful in exerting this social pressure because it was a work place.

Ideological and utilitarian motives overlap with the above described factors but go down more into an individual level.

Ideological motives are quite obvious to discuss because they rely on showing that the people who worked in camps did what they did because they believed it to be necessary and justified simply because they hated Jews and believed them to be a danger and a threat. Within the camp personnel, the simple assumption behind the ideological motives is that someone who went into this line of work voluntarily did so because he believed it was right and necessary, i.e. was an ardent Nazi.

Utilitarian motives focus on the other hand on what was to gain from such violent and murderous actions. I mentioned above that days off for shooting prisoners who attempted to "flee" was an incentive for murder. Similarly, we can glean from narratives of survivors that some guards murdered prisoners to steal their belongings or to force others to do stuff for them (including sexual actions). It encompasses what is referred to within the German criminal law as "lowly motives", e.g. greed, lust, etc.

So, again using Longerich's line of argument, the reasons why the Concentration Camp SS was violent and murderous are related to past socializing experiences especially in regard to violence, which the Nazis were very good at exploiting to form them into ideological murderers while at the same time using quite common motives such as greed to motivate their personnel to become even more violent.

It is important to note that what I have discussed here is a very cursory overview of a lot literature and you will find that different historians either place emphasize on one or more of these factors over others, while some might chose a different explanation (Harald Welzer e.g. relies heavily on social psychology and traits and methods that can be found in virtually every environment, think Milgram Experiment) but as someone who deals with the topic extensively, I have chosen this particular approach because it has been the most useful to me so far.

Sources aside those mentioned:

• Michael Wildt: An uncompromising Generation.

• Peter Longerich: Holocaust.

• Richard Evans' Third Reich Triology.

• Harald Welzer (ed.) Die Täter der Shoah.

While not a scholarly book, "Elli: Coming of Age in the Holocaust" by Livia Bitton Jackson is a well-written and reviewed memoir that includes her incarceration in Plaszow, the camp featured in Schindler's List. She indeed talks about random, daily acts of murder consistent with those in the movie. So, yes, it appears to be authentic and sadly not exaggerated.