I'm curious as to why we don't use heinous criminals in laboratory research? Why is it ethical to perform potentially dangerous tests on an innocent dog, but completely inethical to perform the same tests on a unreformable child molesteror or rapist?

Criminals don't give up all their human rights when they go to jail.

I'm curious as to why we don't use heinous criminals in laboratory research?
i wouldn't have a problem with it as long as the person signed a release and knew what they were doing.
Why is it ethical to perform potentially dangerous tests on an innocent dog, but completely inethical to perform the same tests on a unreformable child molesteror or rapist?
how do you know someone is "unreformable" unless you give them the chance?