I am with Joe and Richard Bridge on this one. There needs to be a deterrent. The best deterrent is the near certainty that the culprit will be caught and sentenced. Getting into bidding wars about how much retribution we should extract is futile. There is no adequate restitution for the loss of a life. If I murder two of your children, surely I deserve to be hanged twice? The desire for revenge, while understandable, can play no part in any civilised justice system. I certainly do not want to emulate what happens in a minority of cases in the USA: A convict first serves a life sentence - and then when time has inevitably changed him into a different person - he is put to death.
Ten years in prison is a traumatic and life changing experience for nearly anyone who endures it. I believe that Nietzsche warned us to beware of those in whom the desire to punish is strong. That is the whole point of taking criminal cases out of the hands of those who are most directly affected by the crime.