All ethical arguments aside, testing it on prisoners would actually be really bad for scientific reasons. All these people have pre-existing conditions and a huge genetic variety. You'd need a lot, A LOT of them to get statistically relevant results.
You'd soon run out of murderers and rapists.
And who's next? Drug dealers? Traffic violators?
I understand where you're coming from but I think we need to look for other ways to get rid of animal testing once and for all