Killing is killing,whether the state sanctions it or not.
The only time I find it justifiable is in times of war, or in cases where certain death is hastened or made easier out of compassion.
It is my view, that if life loses respect, then taking it means little to the criminal.
Also, the criminal likely cares little about losing his/her own.
I believe the State is responsible for the lack of respect for life and property, since it seems to have little respect either.
As to criminals, they are punished far worse by imprisonment and loss of basic rights. Death is the easy way out for them.