A great fucking documentary (besides Mark of Cain) is Blatnoi Mir. Nearly fucking IMPOSSIBLE to see anywhere. At least in the internet.
Illume
It has one of the most depressing scenes I have seen. A young man, maybe in his 23 or something like that is sentenced in the Island Prison for the rest of his life. He, as I gather all the other inmates when convicted there, get to spend one day with someone and then they dont see ANYONE but the guards and maybe other inmates ever again.
The young man spends the day with his mom and when she has to go and they hug, fucking christ... if you ever have searched for visual represantation for the saying
They never wanted to let go
THAT is it. Fuck me, I cried like a little child, but I was older so I cried with more memories and feelings.