There is nothing wrong with rightful vengeance.
But what if they get the wrong person?
Then they get the wrong person.
Shit happens.
Personally, I'm all for placing the most stringent and uniform and consistent controls upon sentencing in capital cases.
To my way of thinking, it would be OK to convict, then serve-up a long (or life) sentence, if convicted 'beyond a reasonable doubt'.
But I would be very much in favor of serving-up the death sentence
only when we're
positive that we have the killer.
A number of wrongful convictions (and even wrongful executions) have occurred because they were so far back in time that various modern forensics tools - such as DNA testing - either did not exist or were new and limited in use or reliability at the time of the trial and sentencing of the accused.
We can take much better care in our application of the death sentence, without sacrificing it altogether.
Such 'better care' is not a rock-solid guarantee that we will
never execute an innocent person, but it will sure-as-hell cut the number to a razor-thin margin, versus what it is
now.
The system would still be imperfect but vastly improved and far more reliable in overcoming objections about executing the wrong person.
The system works well enough now - very few innocent people are actually executed - but I support whatever improvements can be made to the system.