I don't really have a dog in this fight, but I'm wondering if you know if "exonerated" in this case means "found clear evidence that they were not guilty" or just(?) "the conviction was overturned." To me, those are two different things.
To be clear, I don't want anyone in prison (or on death row) that didn't get a fair trial -- even if they're guilty. But I do think there is a difference.
The murderer/rapist was initially convicted and sentenced to death. Effective defense was able to get his conviction thrown out. Normally this would mean you walk free, due to double jeopardy protections. But in this case the murderer was a military officer. Once DNA testing was refined, it was proven conclusively that he was indeed the murderer/rapist. So he was tried in the military court system, which is independent of the double jeopardy protections provided in the civilian court system, and convicted to death - again.
The point I make here is that many of those 190 probably are guilty, and I think this is generally not a bad thing. My main concern with the death penalty is an innocent man being put to death. But if the standard of conviction is sufficiently high that even a guilty man can walk free, at least on occasion, then that gives one some degree of assurance in the ability of an innocent man to prove his innocence.
And yet evidence of actual innocence (https://en.wikipedia.org/wiki/Herrera_v._Collins) isn't enough to stop an execution.
“ Since 1973, at least 190 people have been exonerated from death row in the U.S., according to the Death Penalty Information Center (DPIC). A 2014 study estimated that at least 4% of those sentenced to death are innocent.”
https://innocenceproject.org/innocence-and-the-death-penalty....
We will never know how many innocent people have been executed, but even one is more than I am comfortable with.