Thank you brother Farhan, the article doesn't directly answer the question because it is mostly focused on other things as well (besides the moral aspect).
I found this on Yahoo answers, I thought it would be rather helpful:
The problem is UNDERSTANDING the verse:
In actual the verse is DISCOURAGING capital punishment.
The Torah came with laws of equivalence in the sense: An eye for eye, a hand for hand, an equal injury for an injury.
The Quran has a different law code: It DISCOURAGES capital punishment, but does NOT abolish it.
[2:178]
O you who believe, equivalence is the law decreed for you when dealing with murder - the free for the free, the slave for the slave, the female for the female. If one is pardoned by the victim's kin, an appreciative response is in order, and an equitable compensation shall be paid. This is an alleviation from your Lord and mercy. Anyone who transgresses beyond this incurs a painful retribution.
[2:179]
Equivalence is a life saving law for you, O you who possess intelligence, that you may be righteous.
The objective is to discourage capital punishment.
So IF the heir of the victim insist on capital punishment, then one has to see, if there is equivalence in the matter i.e. the guilty and the victim have to be of the same category i.e. free would be punished if the victim was also free. The guilty slave will be executed ONLY if the victim was also a slave. The guilty woman would be executed ONLY if the victim was also a woman. Else !!! the heir of the victim will HAVE TO accept a compensation, instead.
It is IMPERATIVE to understand AND FAIRLY LOGICAL to understand that you CANNOT punish Paul in place of Peter. This is MADNESS.
And this is a totally ABSURD explanation of idiot Muslims that the Quran in any way is trying to teach us basics in this regard. It is total madness.
Here is a good example that should give the shut up call to such idiots: As this is BASIC justice.
[12:78]
They said, "O you noble one, he has a father who is elderly; would you take one of us in his place? We see that you are a kind man."
[12:79]
He said, "GOD forbid that we should take other than the one in whose possession we found our goods. Otherwise, we would be unjust."