I am slowly coming to understand the hold death penalty has on our minds; we have been brainwashed into thinking of revenge as the ultimate solution, thanks to religion, or more particularly the stories and epics.
Mahabharatam is a tale of unremitting revenge. This is what I learn by watching the currently running serial of that name on STAR TV (its regional broadcasters). There are enough sub-stories woven into the tale, each one founded on someone being wronged and he or she vowing to take revenge. Shikhandi wants the life of Bhishma because it was the latter who left her a spinster (there is enough twist in this tale to spin your head, but the revenge factor filters through clear).
Sometimes this revenge appears in the form of conditional death penalty. Prince Pandu is proscribed from conjugal relationship, and if he trespassed, boom, he is dead! Why? Because he killed someone, in all innocence.
Why does Shakuni win at the game of dice? These are loaded, made by the bones of someone who had severe bones of contention with the ruling dynasty. Bingo! Shakuni takes his revenge and Pandavs are exiled! But, for whatever reason, the script does not lead to extinction of Pandavs.
Draupadi wants Duryodhana dead. Because she was ashamed in the court. Revenge, pure and simple.
In the pre-Ramayan days, we have Parasuram taking revenge against the warrior class for one king slaying his father, killing all (at least almost all) of them. In the epic itself, Sugreev takes the help of Rama to vanquish his brother, to rescue his wife from the latter, and better yet, to kill him! If you do not see revenge in this, well, I cannot help you.
Every religious festival we have is canonized as, “Good over Evil” with the Good triumphant. This is triumphalism at its worst, if you could see it clearly – defining good by who wins! Be it the Ram Leela festival concluding the Navratra, or Deepavali (in the south, Krishna slaying Narakasur). I am sure you can add to the list.
Having so many people die in our tales, we have become immune to death penalty. In addition, celebrating triumphalism, we never accept the possibility of ever being wrong, or having been wrong.
It is this mentality that the anti-death penalty gang has to counter to bring us into the fold of civilization.