I've always believed in the death penalty in principle, but unfortunately the more I see, the less faith I have in our justice system when it comes to highly publicized, highly emotional cases. What I find most disturbing is that prosecutors frequently cannot even "let go" of a conviction in their own mind when a defendant has been proven innocent beyond a reasonable doubt by new evidence.
I used to believe in capital punishment carried out by the State and still think it can be applied under very
limited circumstances. That is why I said I was more in favor of "instant karma" where the would-be perp is taken care of by the would-be victim. I also don't believe there should be any prosecution against the would-be victim for saving the rest of society the trouble of having to deal with the (former) would-be perp. However, in general I have become opposed to capital punishment based on the fact that too many politically-motivated prosecutors and others have provably "railroaded" too many innocent people over the years. People who, through more modern technology, have been proven to be completely innocent. If they had been put to death, there is no way to correct such miscarriage of "justice". As it stands, there is still no actual penalty against those who knowingly "railroad" an innocent person and even though there isn't a penalty against them, as you point out, many of these prosecutors and others remain adamant about keeping the proven innocent person incarcerated! That is disgusting and despicable... and gives the good peace officers and prosecutors a bad name.
So the very
limited circumstances where I am for capital punishment are those (very rare) cases where there is a (non-coerced) confession and/or irrefutable, independently and multiply verified evidence. I know that's a tall order, but without that how can we be certain that some prosecutor isn't just carrying out the charges for their own nefarious agenda. When I was young and naive I would have never felt that way, but the cases where that has happened, for many different reasons, have come to light more and more in recent decades. Now that it takes nothing more than the stroke of a pen to declare anyone
an "enemy combatant" for any
reason... even simply speaking one's own mind, I am even more adamantly against capital punishment. Historically, once people can be incarcerated for speaking up and disagreeing with the powers-that-be, it isn't long before they can be executed for that same "offense".
I am friends with some septuagenarians and octogenarians who grew up in 1930s Germany, so please don't tell me that "it can't happen here". That's what they heard as kids growing up too...