Read the report then. It's long, and I didn't read it all. But I've read a substantial amount and it is very thorough. Family members looking to assign blame will have some targets, though most of it goes to Cho. The report was critical of the school's way of alerting students to what was up, and called out Tech Police for an error in the very initial investigation into the double shooting at the dorm. But the report also said it's understandable how they got that wrong initially and that the police were incapable of stopping Cho.
In fact, one quote says that University and Blacksburg Police saved lives with their actions in the Norris Hall shootings, and that their response there, and really to both shooting scenes, was nothing short of great.