This response strikes at the heart of the issue. Until the wild distortions in the property market are fixed (imo, specifically until Prop 13 gets repealed or significantly amended) big, expensive cities in California will continue have increasing crime problems.
As you can probably imagine, community policing is difficult if you're not a member of the community. And as the cost of living goes up while property taxes remain artificially depressed due to prop 13, the disparity between what municipalities are able to pay for police (which is partially funded by property taxes), and how much those police will need to afford to live there, will continue to grow. It seems like a slow, self-reenforcing downward spiral that will only get re-set if the quality of life deteriorates to the point where people actually start moving out of these communities.