It was even in TV Series .. I forgot title but that moment I remember very clear.
It was shocking. Unbelievable!
For learning more, I personally recommend starting with "Kolyma Tales" by Varlam Shalamov. Aside from the educational part, it's a great piece of literature.
About educational part: it's a frequent misconception. "Kolyma Tales" are not autobiography, it's a fiction.
E.g. His depiction of thieves wars reads as documentary but it's not. There is not a single personage that has direct match in reality. For some: it looks like combination of several real persons, some has no real analogues. The same with events, chronology and geography.
To write a documentary was never the goal for Shalamov.
And keep in mind that it's a perception of Shalamov who always was a man of weak health.
Dostoevsky was in similar or even harsher conditions but he found the strength to see in criminals around him not only infernal bad.
If you suppose that Dostoevsky is not relevant: there are other authors with similar experience.I
For example: Ahto Levi, Estonian, Hitlerjugend on start of WWII, conscripted in SS near end, after war - criminal, repeat offender, member of nationalistic gang -he's one of thieves that Shalamov depicts.
His "Notes by Gray Wolf" shows both degradation to beast and then return to human.
Every once in a while the train stopped, and each stop they asked random people to step forward. These people were executed in front of others. However, majority of passenger have arrived to the final destination (prison camp) alive.
Those who made it alive were never the same, they were broken, psychologically.
Their families too. My grand-grand mother hang herself shortly after his arrest. My grandmother was deeply traumatized for the rest of her life by that (she was a little girl who found her mother hanging from the chandelier).
0 - https://en.wikipedia.org/wiki/Matrosskaya_Tishina