Legal Question in Real Estate Law in California

No easy way. Check with a title company to see if they show any evidence of ownership, mortgages, liens, etc. that might allow you to contact people with legal 'interests' in the property. Check probate records to see if probate was filed, and if he has heirs to buy it from. Wait until the tax agency forecloses in a couple years, and buy it at the sale.

If you were thinking about acquiring title by adverse possession, note that the rules require both payment of the taxes and possession for five years. You are short of five years on the taxes right now, and pretty surely are not in possession of the property. I think having a title company do a search, as proposed by Mr. Nelson, is an important first step. Watch for a tax sale; it might be sooner rather than later.