Nearly two thirds of white people support the death penalty, with evangelical protestants bloodthirstiest of all. Black Americans favor it the least, with only 36 percent in favor of executing murderers. The findings are part of the 2013 Pew survey, in which 55% of Americans say they favor the ultimate punishment for murderers. It's falling fast, though, down from 78% twenty years ago. But it is because of changing beliefs about the morality of killing people, or because there are simply too many appalling mistakes?