Adam Lanza was mentally disturbed and got his guns from his mothers house not by buying them.
His mother should have been warned that guns and her son were not a good mix. She was already afraid of him.....having guns nearby was not wise
Probably so when someone is mentally disturbed they will find a way to carry out their crazy plans the only way I see to really stop someone like this is to be able to have them involuntarily committed which I don't see happening.