Anyone who deserves execution does not deserve a quick, painless termination, they deserve to suffer as much as possible. The only way to make it better is to make them suffer like their victims, and their victims are NOT JUST THE PEOPLE THEY KILLED, but also all the people left behind.
The point of the judicial system is not to exact revenge, but to protect society. I stand with the teachings (CCC 2267) of the Catholic Church on this issue.
2267 Assuming that the guilty party's identity and responsibility have been fully determined, the traditional teaching of the Church does not exclude recourse to the death penalty, if this is the only possible way of effectively defending human lives against the unjust aggressor.
If, however, non-lethal means are sufficient to defend and protect people's safety from the aggressor, authority will limit itself to such means, as these are more in keeping with the concrete conditions of the common good and more in conformity to the dignity of the human person.
Today, in fact, as a consequence of the possibilities which the state has for effectively preventing crime, by rendering one who has committed an offense incapable of doing harm - without definitely taking away from him the possibility of redeeming himself - the cases in which the execution of the offender is an absolute necessity "are very rare, if not practically nonexistent."