For the sake of simplicity, I used "known serial killer" to mean somebody we are certain is a serial killer for whatever reason. Let's say they were at a parade

For the sake of simplicity, I used "known serial killer" to mean somebody we are certain is a serial killer for whatever reason. Let's say they were at a parade, in front of 100 eye-witnesses, and live tv cameras, going around killing people, and then confessed to it to arresting officers and in court. Somebody who is doubtlessly (and perhaps unrealistically) guilty of committing one of our highest crimes, for the sake of simplifying the question.