Well you clearly are impassioned about the subject of the death penalty, but your reasoning is at best muddled.
On one hand you decry the thuggishness of police departments and the over zealous prosecutors like Nifong. Yet on the other hand you decry the unwillingness of society to convict criminals of serious charges because of modern standards of "innocent beyond a reasonable doubt".
You can't have it both ways. Either we continue to be leary of the power of The State to abuse the rights of innocents accused of serious crimes, or we allow the Nifongs of the world to run unchecked. But you cannot keep the Nifongs of the world in check, while resorting to the likes of the dunking bench for determining guilt (I know you didn't suggest that, its a metaphor).
I think you also seem to forget that the definition of a "civilized society" at the time of this nation's founding, was - in Benjamin Franklin's words
it is better [one hundred] guilty Persons should escape than that one innocent Person should suffer
This clearly did not ignore the violence committed by the 100 guilty left free. Rather it weighed the violence that the power of the state can commit against the violence of the acts of even 100 individuals, and decided against the power of The State.
Now I would submit that we have continued to become a progressively more civilized society since that time period. We have recognized the personhood of minorities, women and even children. We have abolished racist Jim Crow, and lynchings are laregly a thing of the past. Violence is down in our nation. The evidence is clearly there that we are more civilized than ever.
Yet by your logic, we should never have gotten here, since Franklin signalled the "death knell" of civilized society back in 1785 when he "ignor[ed] the number of murders committed by violent predators who have been released".
Sorry, it doesn't hold water.