Back when all the botched execution fiasco hit the media John Olliver discussed it and showed the costs of giving someone life in prison versus giving them the death penalty and execution is actually more expensive than holding someone for life. What makes the death penalty so expensive is that the government is required to pay for any appeals that a criminal that is given the death sentace makes. And a death row criminal gets more than one appeal. The government has to pay their court costs, their lawyer fees, transportation fees back and forth to court, and anything that goes along with that and those fees far outstrip the cost of just holding the person for life, because someone given a life sentence is required to pay for their own appeals, lawyers, court costs, and expenses etc.