Another question on this website deals with the issue of kohanim in Auschwitz. To be "strict", a kohen today could simply avoid going to death camps altogether. Elsewhere, however, is not so easy. Are there published teshuvot that address the problems for kohanim of going walking through forests and fields in Poland, Ukraine, Belarus and the Baltic states? Sadly, many of these locations are the sites of mass graves, a great deal of which are unmarked and most of which contain the remains of dead Jews.
I am not a kohen and I am not asking for a psak. I just want to know if there are published teshuvot that speak of this issue, and what kohanim residing in these places do in order to avoid it. My guess is that in most places it's a safek sfeika (safek that the site is a mass grave, plus the additional safek that the people murdered there were Jewish), but in some places those sfeikot collapse into reasonable certainty.
So, for example, while a kohen might not be able to visit Babi Yar, Ponary, Serniki and other such places, does that mean that they also cannot wander through the woods and fields in their environs?