How can I legally investigate my uncle for stealing gold ornaments?

My uncle's family has dug out the basement of our ancestral property and stolen all the gold ornaments without our knowledge. I became aware of this when I saw the debris in the basement. I don't know the exact year when it was dug, as I visited the property after many years. I heard from my father that our forefathers used to give loans against gold ornaments before independence. My uncle, who was an ordinary man, has amassed property worth crores, and I strongly suspect that he stole the gold from the basement without our knowledge. How can I file a case or investigate against him legally, since I don't have any proof except the debris and the assets he has created with that gold? Any legal advice would be highly beneficial for me.