I am far more dissapointed seeing so many stupid liberal do-gooders on this site. As far as I am concerned, if the criminal has committed a murder or is a child molester, then a trip to the executioner is more than deserved. I would also add drug-dealers to this list. These people are scum, why waste taxpayers money on them when all they deserve is a slow death?
But of course I know, a good liberal would rather try to rehabilitate murderers and let them murder more innocent people than actually put an end to crimes.
There is no logic to your post.
As far as the economy (=the wellbeing of the society in general) is concerned, locking up a person has a negative impact (the number of man-hours lost is huge), while killing a person costs even more to the society, because of the involved costs of the trial coupled with the lost man-hours, which would be otherwise spent working and adding value to the economy.
Look up the statistics for murderers, only a small fraction of them re-offend. It makes no sense to kill them or keep them imprisoned, unless they do re-offend. Furthermore, advances in neuroscience and genetics will let us trace the psychos much more effectively. The majority of serial killers, mass murderers etc. are biologically predisposed to commit such crimes with others having suffered severe psychological traumas. It is quite easy to set these people apart from decent people, who've committed crimes of passion (the distinct majority of murders) and who could and should become productive members of the society as soon as possible. Forced labour should be the preferred punishment for these people.
The same applies to child molesters, no reason to kill them, it is irrational. Forced labour coupled with chemical or physical castration should be preferred.