Quote from Roy Fokker
Have you seen how they do it?
Exectution style - one rifle shot straight to the back of the skull.
LINK to picture
[WARNING! That link shows the picture of a person about to be executed. Please Do NOT, I say again, DO NOT click if you might be affected or offended
About the only organ wasted is the brain - I suppose they have transplant teams standing by to preserve organs immediately post execution.
I have seen that photo before. Due to the intense fear and stress of the victims, I have to wonder about those organs. A cascade of chemicals, and hormones would be released just before death. Energetically, at least, that event would effect their organs and impact those who would receive them.