Who should really be held accountable for the death of the teen in Plaza Tower?

A 17-year-old is dead after falling down stairs inside the long-abandoned Plaza Tower, a building that has become a destination for urban explorers. His family says the building was not secure enough to keep teenagers out. So where is the responsibility here? Do people bear responsibility or entering a dangerous abandoned building, or do owners and the city have an obligation to make sure a place like that is truly secured?