Two-thirds of any case involving a black or hispanic killing a white result in the death penalty. Overall, a black person is 5 times more likely to get the death penalty. What we need is a guarantee of no repeat crime. Steven Stack's research shows no brutalization. In fact, it shows that crime goes down after an execution.
Executions add to the glorification of violence that exists already too much in our society.
The methods we use are ghastly. International law prohibits it. Civilized countries don't have it. Even China and the former Soviet states are abolishing it. All humans have an inherent right to dignity and life.