I don’t undestand how they could even attempt to write something that shows any true contrition. Leaving aside the question of whether any of them actually believe that they did anything wrong and feel regret, wouldn't writing any truly meaningful esaay leave them open to procecution? (Although, I guess that would only br a risk if we lived in a world where the police and procecutors give a shit).

How does one even begin with a "I'm sorry I did one of the worst crimes imaginable." essay with a straight face?

I doubt any of them went that far. There's no way they'd admit guilt in an essay. These kids have lawyers.