Legal Question in Real Estate Law in California

Well, it isn't quite true that he has (had) no assets. He (his estate) owns a piece of undeveloped real estate. A better description might be that his estate has no positive net worth, or something like that.

Depending upon the value of the land, and anything else he may have owned, the estate may qualify for a simplified probate process, or may even bypass probate entirely, but with real estate, where there is a formal chain of title, sooner or later someone will question title here if the law is not followed.

I recommend having a free initial consultation with a probate attorney near you.

This is why you should have had the note secured by a deed of trust. When he defaulted, you could have foreclosed on the deed of trust.

You cannot have them deed title to the real property to you, because they don't have title. The estate of the deceased buyer has title, and I'm pretty sure they are going to have to go through probate just to get title. A probate attorney will also tell you to file a claim with the estate. You should consult with an attorney familiar with creditor's claims in probate, as there is a strict short time limit.