What I don't understand is that this was a good looking kid. There should have been no reason whatsoever that he wouldn't be attractive to women -- physically.
The problem he had with women had to be his demeanor, actions, or personality. "Hey baby, let's!" is not a good pickup line for even the best looking guy on the planet.
As to his mental health, the police saw nothing wrong with him and determined that he had no firearms. He schmoozed them and sent them on their way, never giving away who he truly was. This is the way a true psychopath operates and they, not being psychologists, failed to determine his true nature. No one could have determined his true nature in a single informal interview.
There is no blame to go around for the police, the college, politicians, or the NRA. This kid was simply one twisted S.O.B. who flew under the radar.
As for the parents, it seems that they did everything heavenly possible to warn the authorities of the danger this kid presented. All of their efforts were thwarted by his machinations. They must be truly devastated.
Addendum: As for the firearms. He did everything legally. He acquired them legally. They conformed to the state specifications set by the state. The 15 day waiting period was useless. He had 41 ten-round magazines -- all legal in CA.
As for universal background checks, yes, they likely would have caught him trying to buy the firearms if he had been reported. The problem is that those who once were prescribed Prozac as an overactive, and thus, annoying kid would be denied the possession of a firearm even though they would present no danger. There is no happy medium on universal background checks.