The chances are that the kid will be released when he’s 18 and then go on to kill a couple more people. Is that the compassionate thing to do? Transfer our collective guilt to some poor soul who won’t see it coming, wow, aren’t we a caring people.
Jeesh, we don’t want to do the hard thing and put down a murderer because we wonder why “we” did this to him and then later wring our hands when he kills again later. I can see it now: “we’re sorry Mrs. Smith but we found your disemboweled daughter in a dumpster and the killer was someone we arrested for murder 8 years ago but you should feel good about that because we gave him another chance.”
It’s a fact of life that not all kids had perfect childhoods but very few kill people as a result. Could it be that this little murderer who doesn’t care and has no remorse is just plain old evil and no amount of nurturing or intervention can change that fact?