At first I didn't agree with having death penalty. But when you watch the news and see all those fucked up things people do without remorse, most likely you would want them dead too, especially if you're connected to the victims. The only problem is false accusations. Lets say they hang a killer because of manslaughter and after a week later they realized that he wasn't the real killer, well shit. You cant bring the life of that man back. as opposed to just jailing them.
I will say it depends, and I also would say that this is sort of a critical topic because it may touch one's personal, religious, social and life beliefs. Therefore, there is no correct answer, and it would only depend on what's principles. For myself, I would say that I agree, but depending on the what's being punished. Sad to say, but there are so many bad things that call for a stricter much harsher punishment which is done by repeat or habitual offenders. When someone's life is taken or permanently damaged, one should be punished equally because they can't bring back the life lost. Although I agree, it should be viewed very critically because it would also be a way to end one's life, which is equally important even that of a criminal's.
There's a certain problem with this reasoning
That is, do you justify killing an innocent due to some nasty mistake or even willful act just because real murderers should be punished with death? Look, you can't escape from this question or evade this dilemma once there is a possibility of a mistake. And there were numerous cases when people got punished with death penalty which in fact turned out to be another cold-blooded murder. There may indeed be social, religious, or whatever beliefs as well as differences between cultures, but what is your choice, personally?