I just heard on NPR that the school had notified the parents earlier than the day of the shooting that their son’s behavior was disturbing. The meeting between parents and the school was over the fact that school wanted them to withdraw their son, and get him mental help. They left without their son.
It sure does look like that they were informed of a problem and not chose not to deal with it, but increased the threat by either outright buying him a gun, or not locking up their armory.
I had a friend who has two daughters. They each were involved in shooting, shooting competitions, and the youngest was vying for a place on the Jr Olympic shooting team.
When the youngest graduated from HS and was in either her freshman or sophomore year of college she was having mental problems. She was seeing a doctor, and diagnosed with bi-polar disorder. When my friend was telling me all of this I asked her specifically if she and her husband had thought to change the combination on the gun safe. Not sure if they did, but at least I pointed out the threat.