The County Assessor will have a name as well as address. Somebody/something has been paying the property taxes. The name may be an S-Corp, or LLC (or Land Trust if the owner is really smart), but the Assessor will have a name of some sort. If corporation of some sort, you can then trace the owners through the Secretary of State’s Office. (Land Trusts are untraceable to the actual owner - but you will be able to find the name and address of the Trustee of the Land Trust).
Another way to come up with the owner’s name/number is to call the local county inspectors (fire, health/safety, zoning, etc.). Often these people know the owner of the property - especially if the property has been cited for any sort of issue. And California inspectors in particular are often ‘on-steroids’ about citing property owners of all sorts for supposed violations, so they probably know the owner (or at least the owner’s attorney…!).