Death Penalty and Murder Rate

I am willing to forego the emotional satisfaction of seeing monsters get their due, if it is in the best interests of society. As it stands, we cannot justifiably use the death penalty, without resorting to these emotional reactions as justification. Personally, I would be happy to see human monsters punished, even, beyond the level of their own heinous actions. But we live in a society. For the sake of our society’s best functioning, when it comes to the irrevocable action of executing someone, we must do so only in a rational (non-emotional) non-biased way, with no possibility of erroneously punishing an innocent person, or else risk taking on monstrous characteristics of our own. If someone is wrongly executed, we can’t take that back.
Levels of punishment could be up for debate, but the death penalty, IS a black/white issue, metaphorically speaking (and, ironically, literally, as it is disparately imposed on black vs. white people), because death is the ultimate metaphorical blackness.

I am willing to forego the emotional satisfaction of seeing monsters get their due, if it is in the best interests of society. ... For the sake of our society's best functioning, when it comes to the irrevocable action of executing someone, we must do so only in a rational (non-emotional) non-biased way, with no possibility of erroneously punishing an innocent person, or else risk taking on monstrous characteristics of our own. If someone is wrongly executed, we can't take that back. .
So if we have a case where guilt is not in doubt and the crime is heinous how does it harm society to put that person to death?
I am willing to forego the emotional satisfaction of seeing monsters get their due, if it is in the best interests of society. ... For the sake of our society's best functioning, when it comes to the irrevocable action of executing someone, we must do so only in a rational (non-emotional) non-biased way, with no possibility of erroneously punishing an innocent person, or else risk taking on monstrous characteristics of our own. If someone is wrongly executed, we can't take that back. .
So if we have a case where guilt is not in doubt and the crime is heinous how does it harm society to put that person to death? The standard in our criminal justice system is "beyond a reasonable doubt". Reason can often be mis-guided by erroneous evidence and/or by some pertinent evidence being emphasized over other pertinent evidence. So in our system, guilt is, routinely, not beyond all doubt. It is just what has been determined, by a sometimes flawed process, to be beyond a "reasonable" doubt. A society that purposefully kills an innocent person, even on rare occasions, is not, a society to be proud of, i.e., it does not inspire individuals, of conscience, to identify with the greater society. Also, our multicultural and economically disparate society is at greater risk of inter-cultural/inter-class conflict when their is respective disparity in the rulings of our criminal justice system (as is the case). Systemic injustice can sometimes be corrected, but it cannot be corrected for a person that has been executed.