Sick story. Apparently the perps attacked the woman before they 'suspected' she was Jewish from the ID in her backpack. Thinking she was Jewish because she lived in the 16th arr. is a bizarre reason for drawing a swastika on her. The 16 arr. is rife with anti-semitism, just a different kind from the banlieux.
The place where I stayed in France was around that area. If some of these guys think you don't speak French, you're considered easy pickings.