I'll chime in...since I am a cop, grew up as a Christian, and am now a deist!
I support the death penalty...but not via an executioner. So how does that work? If they choose to take their own life, so be it. Don't try to stop or save them.
I know for a fact that there is prison justice for certain crimes. I say let justice take its course once the inmates find out.
Those that quote "eye for an eye" are using the OT to justify a position. However, the OT laws apply to Jews, not Gentiles (non-Jews), so Christians...it seems you can't use that excuse. Besides, God already said that vengeance was His (Romans 12:19).
A life sentence in prison is worse than the death penalty. No more heterosexual sex, no more driving around, no more wearing what you want, no more vacations, etc. You are confined to a small cell, follow a schedule, have tons of boredom, and have the same day in and out, repeatedly...until you die. Let them rot.