Your debtor died intestate. His, or hers, assets will be settled according to your state law. You would be a secured creditor and would/should have rights to your collateral. Any excess you gain above the amount owed you, plus expenses would more than likely go into the estate.
I suggest contacting your attorney and take immediate steps to protect you collateral. You may be able to take possession and sell it back to the relatives - however if there is considerably less money owed than it's worth - state law may require you to sell it for fair market value.
Again, I advise contacting your attorney for the appropriate steps to take.
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The opinions expressed are mine and they are not to be taken as legal advice.