Me, I'm a native of the Lone Star state, now a long-time resident of the East Coast version of the Wild West, and I confess to a great deal of sympathy for this view of murderers and their victims:
The truth is that Texas's propensity for killing its citizens, and its leniency with some murderers, are both expressions of the a single principle. Texas doesn't execute murderers to show its regard for the value of life; it does so because some people (as the parable says) need killing. Sometimes the guy who -- in the eyes of Texas -- needs killing is the accused, and sometimes he's the complainant.
"He needed killin', and my guy was the guy to do it" has long been a viable defense in some Texas murder cases. These are cases in which the State often couldn't secure convictions despite being technically murder; it'll be even less able to secure convictions in the future from juries that know that, if they convict, prison will be the only option.
On the whole though, I'm opposed to anything that smacks of vigilanteism. I don't want to live in a place where people are allowed to, or feel compelled to, take the law into their own hands. But the reality is that some people do kill in self-defense and those people, unless they later get it into their heads that a bullet is the way to deal with everyone who irritates them, are not going to be a danger to me. Turn 'em loose on probation.
Besides, I just plain dislike killin' be it state-sponsored or not. The death penalty, like torture, ought to just be one of those unquestioned and unquestionable taboos that requires no further philosophical justification beyond Dude, we don't do that kind of thing here.