There is two things here:
- The sentence that is questionned by the family
- The problem of the guy not being properly followed by the system (either mental health or police)
For the first point. Its sad, but if expert agrees on the cases, they must have reasons to do so. Personnally I'm always glad to see justice sending people in hospital rather than prison. Its a proof that we are starting to realize that we can have an actual impact and better the conditions of dangerous people. I understand the feelings of the family, but justice is not here to act as a tool for revenge.
Now for the second point, we have here a case were the system is lacking in the detection of potential dangerous individuals. This is not something that is specific to this country but to most country in the world. We need to push more on mental health services and notably on the detection that could prevent such cases to happen.