“In sum, his mother knew her son was psychotic but was allowing him access to firearms.”
Not only that, but allowing him to stay holed up in that basement playing video games all day didn’t help. Mom was not a good mom.
There is the possibility that the mother, Nancy Lanza did lock up the weapons. All it would take is Adam to take the keys when his mother was asleep and help himself to the arms. It has been reported that she took Adam shooting with her to teach him responsibility. Perhaps he noticed where she kept the key when she went to get guns for shooting. Perhaps she put ideas of Adam taking the guns out of her mind and did not consider the consequences of him seeing where she kept the key.
It has been reported that Nancy Lanza bought the weapons for self defense because she regarded the location of her house as a target for home invaders. She may have not considered that the real threat was within from her own son.
I would hope there will be information about Adam Lanza’s mental health and the drug(s) he was taking to manage it. This is the key to why he did it, I am sure. Also, if there was a psychologist involved with his case, there will be those who will bring lawsuits against him for his possible mismanagement of Adam’s mental health. I guess this is why so little is out there about this aspect. When there are lawsuits involved, there is a firm grip on the information.