12.5 billion in fraud? Nah.

It's not just "fraud." She cost people's livelihood, broke up families, and made people homeless directly through her actions. Even speaking as a marxist, banking isn't all intangible made up stuff. There are real individuals suffering consequences, and most of them aren't just rich people doing rich people things.

Personally, I don't think she should ever be allowed to die until she pays back her debt to society. Death is too easy.

Whether the death penalty should exist at all is a separate question, but Marxists generally recognize Engels’ conception of social murder.

When one individual inflicts bodily injury upon another such that death results, we call the deed manslaughter; when the assailant knew in advance that the injury would be fatal, we call his deed murder. But when society places hundreds of proletarians in such a position that they inevitably meet a too early and an unnatural death, one which is quite as much a death by violence as that by the sword or bullet; when it deprives thousands of the necessaries of life, places them under conditions in which they cannot live – forces them, through the strong arm of the law, to remain in such conditions until that death ensues which is the inevitable consequence – knows that these thousands of victims must perish, and yet permits these conditions to remain, its deed is murder just as surely as the deed of the single individual; disguised, malicious murder, murder against which none can defend himself, which does not seem what it is, because no man sees the murderer, because the death of the victim seems a natural one, since the offence is more one of omission than of commission. But murder it remains.

Just about the only thing I agree with for the death penalty. Everything else can be reformed or quarantined. Wealth and power are cancerous. Doesn't matter where they are, they will never stop trying to take over, and total destruction is the only way to ensure they never get loose to wreak havoc on millions of us ever again.

A death sentence is always excessive.

Fraud should be punished heavily though. Someone or several someones probably already died as a consequence of that money missing in the system. I'm not sure if a long jail sentence would be much better, with her being 67 it's a death sentence either way.

In my opinion they ought to follow the money. It's impossible for these amounts to just disappear or to have been used by her. It would make sense to keep her alive if there's any chance of recovering more of that lost money. But maybe that's the point.

I don't think anyone should suffer the death penalty, but I also think that there must exist some amount of generalized damage that is enough to cause surplus deaths

Absolutely.