Apparently the Wisconsin Jewish Chronicle published an article saying Rosenbaum's family hadn't been practicing jews for several generations. A link to that article is gone, however. Did the article exist? I don't know. His arrest records mark his race as unknown. He had been arrested or a number of things, including sexual molestation of a child. So, there's no direct evidence it seems, that he was a jew. But if it looks like a duck, and quacks like a duck...