Book by Jewish historian Arthur Koestler, explaining how the Ashkenazi Jews are not real Israelite Jews, but are the progeny of the Khazars, a European/Turko people. This book was aptly named The Thirteenth Tribe to show that more than 90% of today's Jews are not descended from the Biblical 12 tribes of Israel. The implications of this are far reaching in that it shows that the majority of Jews, especially in Israel, are not Semitic and cannot have any real claim to Palestine.
In 1983, this author and his wife were found dead in their London home. Despite strong evidence to the contrary, it was ruled a double suicide. A motive for their murder is apparent. It is further apparent that someone took this book seriously.