The cost involved in putting someone to death far exceeds the cost of having someone imprisoned for life.
Do you have proof for this statement?
You state it as if it were a fact, and I'd like to see your source if you would care to share it with us.
Financial Facts About the Death Penalty Defense costs for death penalty trials in Kansas averaged about $400,000 per case, compared to $100,000 per case when the death penalty was not sought. (Kansas Judicial Council, 2014). A new study in California revealed that the cost of the death penalty in the state has been over $4 billion since 1978. Study considered pretrial and trial costs, costs of automatic appeals and state habeas corpus petitions, costs of federal habeas corpus appeals, and costs of incarceration on death row. (Alarcon & Mitchell, 2011). In Maryland, an average death penalty case resulting in a death sentence costs approximately $3 million. The eventual costs to Maryland taxpayers for cases pursued 1978-1999 will be $186 million. Five executions have resulted. (Urban Institute, 2008). Enforcing the death penalty costs Florida $51 million a year above what it would cost to punish all first-degree murderers with life in prison without parole. Based on the 44 executions Florida had carried out since 1976, that amounts to a cost of $24 million for each execution. (Palm Beach Post, January 4, 2000). The most comprehensive study in the country found that the death penalty costs North Carolina $2.16 million per execution over the costs of sentencing murderers to life imprisonment. The majority of those costs occur at the trial level. (Duke University, May 1993). In Texas, a death penalty case costs an average of $2.3 million, about three times the cost of imprisoning someone in a single cell at the highest security level for 40 years. (Dallas Morning News, March 8, 1992).
It seems like common sense that its cheaper to execute someone than to house, feed and take care of them for the rest of their natural life. But there are a lot of unavoidable costs that make a death sentence far more expensive than a sentence of life without parole.
Most of these costs result from the unique status of the death penalty within the US justice system. Because its the only truly irreversible form of punishment, the Constitution requires a long and complex judicial process for capital cases, including several levels of mandatory review after a death sentence is issued. The appeals process takes decades to complete.
Studies of the California death penalty system, the largest in the US, have revealed that a death sentence costs at least 18 times as much as a sentence of life without parole would cost.
(Source - deathpenaltyfocus.org)
[C]apital cases (those where the death penalty is a potential punishment) are more expensive and take much more time to resolve than non-capital cases. According to a study by the Kansas Judicial Council, defending a death penalty case costs about four times as much as defending a case where the death penalty is not considered. In terms of costs, a report of the Washington State Bar Association found that death penalty cases are estimated to generate roughly $470,000 in additional costs to the prosecution and defense versus a similar case without the death penalty; that doesn't take into account the cost of court personnel. Even when a trial wasn't necessary (because of a guilty plea), those cases where the death penalty was sought still cost about twice as much as those where death was not sought. Citing Richard C. Dieter of the non-partisan Death Penalty Information Center, Fox News has reported that studies have "uniformly and conservatively shown that a death-penalty trial costs $1 million more than one in which prosecutors seek life without parole."
And let's not forget about appeals: in Idaho, the State Appellate Public Defenders office spent about 44 times more time on a typical death penalty appeal than on a life sentence appeal: almost 8,000 hours per capital defendant compared to about 180 hours per non-death penalty defendant. New York state projected that the death penalty costs the state $1.8 million per case just through trial and initial appeal.
It costs more to house death penalty prisoners, as well. In Kansas, housing prisoners on death row costs more than twice as much per year ($49,380) as for prisoners in the general population ($24,690). In California, incarceration costs for death penalty prisoners totaled more than $1 billion from 1978 to 2011 (total costs outside of incarceration were another $3 billion). By the numbers, the annual cost of the death penalty in the state of California is $137 million compared to the cost of lifetime incarceration of $11.5 million.