The Holocaust survivor
As I recall, they didn't explain in the film the meaning of the tattoo on the forearm of the jeweler (or antiques dealer?) that Wells tried to sell the jewels to. Wells, the character, certainly wouldn't have had any idea what it was from, but I guess most (or many) in the audience would have, back in 1979.
However, I suspect most audiences today would not understand the significance of the tattoo in that scene at all.