To the tragic relatives of the slain - I recommend that they must try to forgive - but this may become problematical for many where repentance is absent in the perpetrator.

You cannot bring back the dead - and certainly some relatives would not want to see a death sentence imposed - but it is NOT for them to say. Society should take the lead and there is a desperate need for a social purging.
When you have a death penalty - even if only very rarely used - you have a chance to deal with situations of this type. Where there is none, you have painted yourselves into a corner and have no mechanism for justice.
There must be retribution - which is cold, neutral and clinical. If neutral, then it is justice and not revenge.
Effectively, the absence of capital punishment is a statement that evil is actually within the bounds of what can be tolerated.
Please pray for the survivors and the relatives of the dead. (Do not pray for the dead themselves.)Whether the perpetrator of this deed is capable of repentance - I severely doubt - but Christians MUST pray for God to have mercy on him on the celestial level. Sorry - but that is what we do! We desire that he should truly repent.
Christians have to differentiate between the role of the individual and the role of society. THEY ARE NOT THE SAME!