Gee.
“Gun laws in California regulate the sale, possession, and use of firearms and ammunition in the state of California in the United States.
The gun laws of California are some of the most retrictive in the United States. A Handgun Safety Certificate, obtained by passing a written test, is required for handgun purchases, although there are exemptions to this requirement. (This requirement was extended to long guns on January 1st, 2014. Handguns sold by dealers must be “California legal” by being listed on the state’s roster of handguns certified for sale. Private sales of firearms must be done through a licensed dealer. All firearm sales are recorded by the state, and have a ten-day waiting period. Unlike most other states, California has no provision in its state constitution that explicitly guarantees an individual right to keep and bear arms”
http://en.wikipedia.org/wiki/Gun_laws_in_California
Since -- like all the recent mass killers -- it sounds like he was bat**** crazy, is it a giant leap to speculate that the gun might belong to mom or dad?