Keeping someone alive in prison for a number of years whilst he waits his turn to be executed is torture. In Islam, as far as I understand, to avoid this wait, the capital punishment should be carried out as soon as possible after the judgement has been made.
With regards to punishments in Islam being torture, I don't believe they are. They are defined, swift punishments for crimes which corrupt society.They bring about justice. Its because we do not deem these crimes as particularly bad anymore that the punishment appears over the top and barbaric. Suffice to say there are always many conditions before the punishment can take place and I'm no scholar to say much more..
But this is going off topic as the question is capital punishment vs life in prison. For that I believe capital punishment is superior in every way to prison. Wether it be due to the detterent effect of the execution or simply the cost saved with imprisoning hundereds if not thousands of criminals indefinitely. There are always the options of blood money or forgiveness.
My opinion on the punishment of the rapist would be to finish him off. I do not think any parent, man or woman, could remain sane after knowing that their child had been raped and the rapist was still around. It reminds me of gary plauche
who exacted revenge on his son's rapist in front of the cameras. Check the link for the video.
- I do not know what the shariaah ruling is myself but suffice to say we have punishments defined for us according to Islam, not based on our own emotions and ideas of the world, but divine wisdom.