A lot of the comments down here say all my questions already.

How the crap didnt all these people serve their whole sentence?
All of this is so damn disturbing, especially that all the kids are involved. This is neutured behavipr, taught behavior making them into miserable humans. Not only Sylvias life ended, but Gertrude mades these kids into monsters. Imagine what that does to kids.

Same as what @mysted says: immediately lord of the flies came to mind by me. But also the Stanford experiment with the two groups of students, feom which 1 group were turned into prisoners and 1 group into guards.
Power does a lot of nasty things to people.. yuk!