To quote Mohandas Karamchand Gandhi, the father of our nation, "Forgiving is more courageous than punishing. The weak cannot forgive; forgiveness is the prerogative of the strong."
Although criminals do make blunders and crimes, this reflects their wrong, rather different, perspective of crime. The must not be punished; instead, they should be enlightened about the "goods" in life and should be given another chance to walk on the path of goodness and virtuousness.
So, I would like to conclude by saying that, criminals are guileless and not wicked, and that they deserve, not punishment, but learning.