I don't have the facts and figures to give you but it does cost more for the appeals and for the innocent family to go through the death penalty fiasco.
If he were put in jail with no possibility of parole, it will be finished all that much faster. The Van Daame family won't have to hear about it every day for the next 20 years. That little girl is dead, there is nothing that will bring her back, not even his death.
He deserves pain, but he won't get it. He will be well protected while they do all those appeals and even if the time ever does come, it'll be painless.
Just get him out of the media, out of their face so they can continue on with their lives, what's left of them.
Get him in jail and we can hope the rumors are true.