Agnieszka, the Holocaust project is very much aware that there were many thousands of non-Jewish people who were victims of that atrocity, which is a fact often overlooked by the rest of the world considering the Holocaust as a genocide perpetrated against Jews because they comprise such a large proportion of the victims.
For better or worse, the project has deliberately not made any attempt to classify victims by their religion. For this reason, I would recommend that you categorize the person by the camp in which they died. The pertinent facts that led to the person's imprisonment, if known, should certainly be discussed in the profile's biography section.