intestate personal property

My son died without a will in California. He had no children. He had a domestic partner of 12 years who was joint tenant on his house. I understand that the domestic partner gets the house as the surviving joint tenant, but I understand that I have a right to claim my son's "personal property."

How do I determine which things within the house were my son's "personal property"? The domestic partner is being uncooperative and won't let me enter the house to look around.

Thanks!