When we all bought properties on this sitesi, there were some owners that nobody was in contact with, & we were needing to set up a legally recognised sitesi ASAP. Our (then) solicitor, was able to get the info from the tapu office at the belediye.
Moving on to current times, our (now) solicitor has told us that either he can do that search for us, for a fee or our baskan can do it for free.
In summation, assuming that you have the name of the deceased & the area in which the property may be, a solicitor should be able to do the search on your behalf
