Bring back capital punishment

I think keeping a murderer in prison for 20, or so years, at a massive cost to the public purse is all wrong.
Last October, a thug brutally murdered my stepson. He was sentenced to 20 years.
Me, and every other tax payer in this country is paying (through taxes), for this piece of scum to live in the lap of luxury, with all mod cons.
My wife,(the deceased's mother), will never recover from this, especially, after losing her son's identical twin brother to cancer 5 years ago.
My wife is a broken women, she think's of nothing else, as to how her son died. Did he suffer? etc.
I think keeping scum like him is a waste of tax payers hard earned money.