How many death row inmates have been subsequently proven innocent of the crime they were convicted of? How many other death row inmates who deserved to be declared innocent have no hope of having that fate? And how many executed inmates were later proven to have not committed the crime?
In our imperfect criminal justice system, people who are innocent and have no means of maintaining appropriate defense are doomed to face a higher probability of getting death sentence. Poverty and discrimination cause innocent people to end up wrongly convicted and wrongly sentenced to die.
Death penalty is not the only means of punishing those who have been proven beyond any reasonable doubt of committing the serious crime they were charged of. Life sentence deprives a person of much of the human rights and freedoms many people could enjoy. Lifetime imprisonment is a harsh punishment, even in the best, modern and humane prison facilities. And it is a better option than death penalty.
Death by execution is an injustice to an innocent person. It is an easy way out for government that has the responsibility of finding the culprit, and having the appropriate punishment served with due process properly respected.