Well, the death penalty is a very controversial issue, and bound to evoke never-ending debate from both sides of the issue.
For me personally, I am opposed to the death penalty for these reasons:
a) Nothing will bring the victims back.
b) It would not serve as a deterrent, unless we were to live in a police state. For example, the Soviet Union, where people were genuinely concerned about the KGB monitoring their every move, in private and in public.
As it stands, by the time the sentence is actually carried out, the crime had already occurred decades ago, and is not fresh in the memory of the public.
c) It is not cheap. A death row inmate will still cost the state money for his room and board. And his constant stream of appeals tie up the courts, and run up legal bills, which usually, the state must also pay for.
d) Risk of mistakenly executing an innocent man.
e) For the government and vengeful families to purposely take away someone's life in an act of vengeance, disguised as punishment, drags society down to the level of the despised monster.
In other words, it makes us as bad as him.