I almost wish we'd hold criminal executives in the US accountable to a similar level. Many have destroyed and indirectly ended far more lives through malice than any direct murderer ever will.
Its only purpose is revenge, and that has no place in our legal system.
Instead, this criminal should be removed from society so he no longer does harm (jail), and it should be studied why he committed those crimes, and we should attempt to rehabilitate to learn more about how to build a better society.
1) First, fear is a motive to not commit those crimes. 2) Second, it's purpose can be to completely get rid of the evil that he or she was. If you kill the person, there's no more of his evil. Wealthy or powerful evil people can have devastating and evil effects on so many people, and so it might not be worth keeping them alive.
If you or your family have enough money (and we're not even talking about the billionaire, or even tens-of-millionaires here, but far smaller sums of cash), prison is merely a speed bump.
Locking him up would mean keeping an enemy of the state alive, an enemy with powerful friends and a very large bag of dirty laundry.
This isn't justice (this is Iran were talking about after all it's judicial system is a joke) this is spring cleaning, the sanctions have been lifted so he isn't needed anymore.