It just seems to me that the pro-arguments are not consistent at all, and the people who argue for it, don't seem to have really thought it through.
The way I look at it, if it is revenge, it is a poor example of it. If someone killed your son, killing that person does not cause him the same suffering at all - what would fit better would be something more along the lines of killing someone the killer loves. Of course that wouldn't be fair, would it? Ruining his life perhaps - wouldn't life in prison be a better means to that end than death?
If it is retribution, what reward are you getting from killing this person? Do you get a measure of joy from people dying? Are you not the same as the killer, then? Retribution for the loved ones of the victim perhaps? That seems awfully barbaric to say the least. Plus it seems to me that the loved ones wouldn't really benefit from this person dying. Furthermore, what if someone kills a homeless person or hermit with no loved ones? Should the killer go free? There is no one to offer retribution to.
The only possible argument I could see for capital punishment is simply to remove the person who has proven they can not or will not be a functional member of society. If they can not, it seems rather cruel to kill them for deficiencies under their control. If they will not, that implies that rehabilitation is possible.
I have to admit, that when I hear of someone committing a murder for pathetic reasons that I do not think is any justification, I shed no tears for their death. On the other hand, as Asguard pointed out, this particular guy appears to be an ideal candidate for some sort of ambassador program to speak to troubled kids.
The biggest problem I have with those who condone capital punishment is that most of them, in my experience, do not look at what causes the problem, they just look at the results of the problem and want them to go away.
Our greatest responsibility is to protect the innocent from the malevolent, correct? Isn't that the point of locking up violent offenders? If that is so, shouldn't we be looking at the issue pragmatically and attempt to determine how to best achieve that goal?
If you have a disease, you can treat the symptoms or the causes.
A discussion of captial punishment is woefully lacking if it does nto include the topics of rehabilitation, crime prevention and fighting the causes of the crimes.
Keep killing the criminals and there will always be more criminals - it keeps no one safe.
Figting the criminals is only a very small part of fighting crime, you have to fight the crimes themselves by digging them out by their roots.