tenant died without will

I'm a landlord in New York State. My tenant recently died, and I believe he did not have a will. His brother, a convicted felon in prison, gave me a notarized letter authorizing his children (the tenant's neice and nephews) to remove the deceased's belongings from the rental house. The tenant also has an estranged sister in North Carolina. I need the belongings (there's very little) out of the house so I can prepare to rent it again. The rent is paid through the end of June. How should I proceed? Can I give the property to the brother, or do I need to track down the sister to see if she has interest in the belongings? Does a court need to appoint an administrator? What's the quickest way for me to get the stuff out, and not become involved in the family matters?

Inventory the property and put it into a safe storage. Send (certified RRR) the brother AND sister a copy of the inventory and a letter giving them a reasonable time (10 days) to contact you about recovering the deceased' property.
New York also has all kinds of laws as to rent control, etc. so you should also talk with a NY attorney to see what legal obligations you might have.