Earlier quoted context omitted.
The analogy is closer to being: the state will prosecute the murder victim's family for failing to properly protect them AND won't be able to locate or punish the true murderer. So in this situation, what's the family going to do? Mourn in private and not report the crime, maybe try for vigilante justice if they think they've identified the murderer.
And not let the community know there is a threat out there.
Reporting the murder will see the community punish the family for not protecting the person better.