Legal Question in Landlord & Tenant Law in California

If the dead person was your former tenant, then you need to deal with his or her estate. You probably need to bring a claim and then file the lawsuit. There is limited time. You should probably contact a local probate or landlord-tenant attorney. The death makes the issue more complex than a standard unlawful detainer.

No. You cannot sue for unlawful detainer unless occupancy of the premises is in dispute. A dead person obviously cannot be claiming a right of occupancy in violation of the landlord's right of possession. So you must file a straight contract case if you need to sue the estate.