Buddhism directly does not support any kind of harm to anybody even to animals.
But Lord Buddha, in his discussions of preventing oneself from doing evil, has stated fear of punishment is one way. The other ways are fear of getting blamed by oneself, fear of getting blamed by others, fear of the karma concept - the idea that what you do to the others - good or bad - will come to you in this life or in future lives The last one is true only if the person believes in rebirth / reincarnation.
Lord Buddha never asked the kings, who were loyal to him and were prepared to do anything he asked, to stop any kind of punishment including death penalty.
Once, some Buddhist monks came to Lord Buddha and described with great sorrow how the people under punishment were suffering. He kept quiet showing that he had nothing to do about that.
Buddhism does not support the death penalty. Buddhism is supposed to hold life in high regards, however, they have used the death penalty before. There is limited Buddhism support in the country that uses this end of life sentence but from a faith perspective I do not believe that they support the death penalty but have not done anything to stop it.
I do not know a whole lot about Buddhism but they seem to be pacifists for the most part. So, I do not think they would agree with or support the death penalty. I think that they would also feel that we could not put a person to death when there is a chance they are innocent.
Buddhism honors all life in its glory, no matter how small and no matter how evil. Buddhist monks take this to the extreme--they don't even kill mosquitoes that bite them on the arm! Certainly, not all Buddhists adhere to the interpretation that all life is precious. However, in general, every major religion embraces the sacredness of life above all else.
I don't believe that Buddhism supports the death penalty. As far as I understand Buddhism, one of the core tenets is to live and let live and to cause no harm to other living beings. Many Buddhists are vegetarian because they don't believe in harming animals. I don't think there is any room for justifying the death penalty for humans in Buddism.
I do not believe Buddhism supports the death penalty. Buddhism, as a religion, contains texts that ask you to only read them and decide for yourself if you believe them. It is not a religion of rote right and wrong and does not seek out to judge anyone, not even the criminal.
No, Buddhism does not support the death penalty because they are all about peace and that is not peaceful to have lethal injections. I don't think that Buddism supports the death penalty because those people are just too peaceful to support the death penalty. Buddhism is a religion of peace.