We only feel pains when we are alive. The deaths did not know no pain and that means deaths penalties served no purpose than separation from the body which is better. Putting criminal behind bar is far better and that is a good punishment well deserved for criminals and criminality. Capital punishment serves no purpose than creating enemies and regret.
When government want to keep a criminal in a jail for 20 years it will be cost a lot so better take them into hell will be a good solution.
When someone already did crimes then chances of being into a good soul is less but atleast their death will be a good lesson for the people who thinking about making crimes.