Scenario:
You're home watching a show on tv with your pregnant wife. You being security conscious have cameras ALL over the place, so when two men break down your door their faces are streamed to the cloud and the alarm company dispatches police to your place, but when they arrive, the two men are just finishing the rape and one of them guts her like a deer as the police rush in. She dies in your arms and your unborn baby inside her.
The men surrender and the video and physical evidence, plus the apprehension on scene, there's absolutely zero chance of any error in who did what. They confess to 287 other rape/murders, mostly kids between 5 and 10 (including cannibalism!) and provide ids and locations of most of the corpses. They're sentenced to death.
Remember. These men have been raping, murdering and eating their victims for DECADES and the proof is absolutely incontrovertible. Hell, you didn't even NEED cameras because they video taped themselves doing most of the murders. The oldest murders were on Super-8 film!
I won't take the job of pulling the trigger, unless the victim(s) were family/friends, but I have no issue with the death penalty. I do have an issue with the standard of proof used. I do think there should be solidly incontrovertible, physical evidence, not "he said, she said" evidence.
IANAL