We got rid of capital punishment for murder somewhere around 1965, although it hung around for some bizarre crimes like setting fire to HM Dockyards for a few years after that.
Now you're going to re-introduce it for a new crime. Not for murder, but for having a brother, son, father etc who is a murderer.
Oh dear, here I go, feeding the trolls. Please tell me you're a troll and not a raving lunatic!