He ran away from home at sixteen (maybe a little younger not sure) because he was being physically abused by his father. There is a general understanding in my family that he fought against the nazis at some point during the war, but no one seems to really know the details as he never talked about the war. He died in 2008 and I have been wondering about his story. I know that many Romani people were killed in the concentration camps and I know he was at least part Romani and had distinctive black hair and tanned skin. What is the likelihood that he was in a concentration camp given the tattoo ? Is there any other possible explanation ? Im planning on speaking to my grandmother about it explicitly later today, but she has a hard time talking about the war as well as she was forcefully relocated to Germany at around seven to eight years old during the war and forced to work in a factory and may not be very open to talking about it.
EDIT: Just to clear up something - I am not going to "interrogate" my grandmother and understand that talking about traumatic experience is not something that should be forced (I am in grad school to become a clinical psychologist and work a lot with trauma survivors).
Auschwitz 1, which had a large number of non-Jewish Polish prisoners, mostly people working or thought to be working with the underground, it is highly likely he was imprisoned there, as it was the only camp which used the tattooing system. If the series of numbers began with an "A" than it was definatly Auscwitz, but the numbering system wasn't standardized for the whole war so even if this was not the case it was likely he was imprisoned in Auschwitz 1 or Monowitz. Since he was Romani, he may also have been imprisoned in the so called "g*psy camp" in Birkenau, in which case his number could have begun with a number, an "A" or a "B". The Romani camp had a fairly high death rate, so it is somewhat more likely he was a political prisoner in Auschwitz 1 or Monowitz, but any of these is a possibility. I hope you're able to find some information, I would say the Auschwitz museum is a good place to start, as is the US Holocaust Memorial Museum.
Is it appropriate to politely request an update if OP's grandmother is comfortable sharing her story? A first or second-hand account is, imo, invaluable information & I would be interested to read about her experiences during such a tragic time