I would support the death penalty for the current perpetrators of this mass crime against humanity. US law, however, does not allow such retroactive application

I would support the death penalty for the current perpetrators of this mass crime against humanity. US law, however, does not allow such retroactive application of the law for many good reasons. The perpetrators should be tried in international court like the Nazis were. In the end, let's not forget that their goals were essentially the same.