Setting aside the moral/ethical of the death penalty versus life in prison, from a cost basis alone, the death penalty is bad policy. It costs far more to put someone to death than it does to incarcerate for life. There’s the legal costs/fees of appeals, the special treatment in prison for death row inmates, and those add up.

In fact, it can be significantly more expensive to do the death penalty than to sentence to life in prison without parole.

deathpenaltyinfo.org

But once you factor in the fact that there are an increasingly large number of cases that have been overturned due to DNA evidence, improper police procedures, etc., a death sentence would not be corrected should someone be exonerated after they’re executed, means that life without parole should be an appropriate sentence for the worst offenders.