If the guy wants to die like that its his choice.
On the death penalty itself my issue with it is i don't think murderers and rapists deserve to die.
In this case i use the word "deserve" as "You don't deserve a Christmas present this year because you've been a little shit timmy"
Convicted Cold blooded murders(because sometimes murder isn't heartless.. still wrong but not sinister... i don't want to get into that though... its long...) and rapists(No excuse) should be stuck in a cell barely big enough for them to move, hooked into a wall, and fed through a tube. Total darkness, total silence, unable to move, jaw wired shut so they can't even hear there own voice. Just alone in the shadows, until their last breath.
Yes, i have a very narrow view of serial killers and rapists. I want them to suffer.
Best of all the system is cheap. A standard prison could house ten times the amount of prisoners. Even safer put it underground so its not an eyesore. The lack of movement and real food would make them so weak that even if they could get out of there restraints the layers and layers of concrete and steel door would lead them to just starving to death slowly deep below the earth in utter darkness.