I agree with the death sentence in certain cases (repeat rapists ... violent premeditated murder..... serial murderers... etc).
However, if anyone commits false witness that leads to an execution of an innocent -- that person also gets executed (no leeway).
In my personal opinion - life is not that special. There are near 7 Billion people on this planet and if someone is simply a scourge to society -- remove them like you would a rabid dog.