Yes, there is a very clear answer--capital punishment doesn't work. It may reduce crime in certain areas for a short period of time (even that can't be totally agreed upon), but the fact is--killing will always occur.
History has shown that all forms of capital punishment (public executions, public hangings, gas chamber, etc.) have accomplished nothing. It is much better to try and help these and other criminals (let's try using the word "people") return to society after serving beneficial jail and/or prison time. This can be performed at least by giving them counseling and teaching a skill or trade (with a guaranteed job).
We can't stop the killing, but we can rise above the hypocrisy and "panic judgment" that say "kill those who kill."