This ain't the question we should be asking tho, no? A person that already raped a child or committed a murder he no place in society (or in the world altogether)
There are multiple different degrees of murder and mitigating factors that could cause a person to be released instead of spending life in prison. I guess if you want an example of such a murder, Gypsy Rose Blanchard is probably a good example.
Regarding rape in particular(child or otherwise), I think justice should first and foremost focus on the needs of the victim. If the damage done is so great that the victim feels the abuser should be put away forever, I think that's fair. But if that's not the case and the victim forgives the abuser in some form and is okay with the abuser getting 5 or 10 years for what they did, I think that's also fair. I don't see how an outsider who has no connection to that specific case has any right to object to that.
I don't know to what degree victims really get their needs honored by the system. My best friend is a lawyer and he's worked with domestic violence victims. From what he told me, it was pretty hard to get his client justice because her abuser's lawyer was playing really dirty.

