So I was reading about Nazi human experimentation, and whilst it struck me that the methods used were obviously wrong, some of the data they gathered could be useful. The problem is that no one would consent to it. So should we do it to murderers? They've already lost their right to a normal life, and in some countries they're going to be killed anyway - wouldn't it make more sense to use them to gain useful medical knowledge?
Obviously theft and such isn't serious enough to justify this, but if someone is a murderer, I say why not. Karma tbh.