This makes no sense. Some people deserve killing--by the state, in the execution of justice. Life in prison is not punishment, it is a reward, and it is a burden in cost to the taxpayer.
Make sure the person is guilty beyond a doubt,yes--but execute justice. To do otherwise is to break faith with the citizens who are told not to take the law into their own hands.
The state has an obligation to protect its citizens from murderers, and to mete out justice.
Even if you could argue justified killing by the state, the fact that a poor person is much more likely to be "worthy" of execution is indefensible.
I find it incredibly ironic that conservatives who want the government out of our lives also think they should have the ultimate power of life and death upon the people.
If you spent one night in prison, or even walked through one, you would not wish that "reward" on your worst enemy;