After Us Weekly uncovered a 2004 snapshot of Jesse James dressed in a German Nazi hat giving a "Heil, Hitler" salute last spring, the motorcycle mogul, 41, denied claims of anti-Semitism.

But now Us has discovered new, similarly disturbing images involving James, posted on Facebook by ex-employees of his company, West Coast Choppers. In one pic, James grins and sits in a convertible alongside a pal who gives the infamous "sieg heil" salute; another image features a children's book character, Flat Stanley, dressed as Adolf Hitler.

The chilling photos are featured in the new issue of Us Weekly (on stands now).

"He's into history," an insider explains of the undated pics, which were posted in October.

Adds the source, who insists James isn't a skinhead, "The swastika deal is to scare people. It's part of biker culture."

For more on James, including how ex-wife Sandra Bullock found out he was engaged to new gal pal Kat Von D, pick up the new issue of Us Weekly -- on stands now.