He's already lumped with killers, of sorts---still killers whichever way you look at them. Those who admit guilt do usually get their sentences reduced, or released on condition/licence.
So does he cling to being innocent which, in all likelihood, will afford him higher status in the prisoners' hierarchy, and earn him some respect, PLUS the chance to get out, eventually and claim compensation, OR does he admit guilt, drop like a stone in the hierarchy system, become just another child killer, and take the retribution for fooling other prisoners, get early release IF he's still alive but with no chance of compensation. I think I know which one I'd go for.