First, you must know the date of death. This is the main condition! Otherwise ordinary people (without connections in the police, the Registrar or funeral Director) to produce such data practically impossible. Because in the office of the cemetery is (it's still a big question mark) in special accounting books of the dead by date of burial, not of birth or last name.
First, still contact the Registrar's office. With a certain degree of luck, you will find there a copy of the death certificate, which must be the date of death. That's half the battle. Well, after looking at cemeteries...
But if you are a close relative of the deceased or a representative of law enforcement bodies with special permission, this copy of the death certificate you are unlikely to get. As they say, then under what kind of mood you will get. You can expect to as a "miracle" and the notorious "Murphy's law".
There is another option. But it will cost you a certain sum of money.
You can hire a dedicated personor team of people who will deliberately go looking for the burial place of the desired person. You don't have personal experience with paper and archival tape, the modern bureaucratic system. On average, the search time is 3-4 weeks. Although, in principle, the possible time for the search is not limited, unless of course you don't need this information urgently. The cost of such services varies depending on the complexity and duration of the process. She is approximately 5 thousand rubles. But in any case, it is likely that neither you nor employed by you, the people did not find it.