Adolf Hitler is thought to have made war on all Jews, even people who were only "partly Jewish." Mr. Rigg in his new book calls this assumption into question.

Throughout Hitler's political career, he made several exemptions from his ideology. Whatever Hitler had written into decrees was always subject to alteration at his discretion. Hitler granted thousands of Mischlinge (partial Jews) exemptions from the provisions of his racial laws.

Some have claimed that Hitler made exemptions for Mischlinge because of his own "Jewish" past. Since this issue was raised frequently during discussions of this study, it is explored in some detail. The facts seem to indicate that Hitler feared his paternal grandfather was Jewish. As Dr. Fritz Redlich, psychiatrist and author of Hitler: Diagnosis of a Destructive Prophet, said, "Hitler was mixed up about his descent. He was definitely scared about the possibility that he had a Jewish grandfather." However, no documents have survived to confirm or deny this allegation.

Hitler may have given exemptions to Mischlinge because of his own experiences with them and Jews. Hitler spent time and possibly was romantically involved with quarter-Jew Gretl Slezak. He had met the Austrian Jew Dr. Eduard Bloch, who took care of his mother during her battle with cancer. Hitler respected Bloch. After the Anschluss in 1938, Hitler made sure that Bloch was protected until the proper documents had been procured for his emigration. Hitler saw to it that Bloch, whom he called a "noble Jew," could leave Germany unharmed. Hitler may also have given exemptions to Mischling soldiers because of his contact with Jews during World War I, through which he learned how brave many of them had been. Hitler received his EKI on the nomination of Hugo Gutmann, his regiment's adjutant, a Jew. Such firsthand experiences may have motivated Hitler to give exemptions to some Mischlinge.

Hitler had shown from the beginning of his political career a tendency to make exemptions. Between 1920 and 1933, he usually granted them because of political necessity. He allowed Ernst Rohm to command the SA even though Rohm was a homosexual. Although those who were homosexual were later marked for persecution, at this stage Hitler believed matters "purely in the private sphere" should be left alone. Perhaps the most famous exemption was given to Heydrich, the "Blond Beast," head of the SD Reich Security Main Office and one of the architects of the Endlosung.

When Heydrich was a child in Halle, neighborhood children made fun of him, calling him "Isi" (Izzy), short for Isidor, a name with a Jewish connotation. This nickname upset Heydrich. When he served in the navy, many of his comrades believed he was Jewish. Some called him the "blond Moses." Others who lived in Halle have claimed that everybody believed that his father, the musician Bruno Heydrich, was a Jew. Half-Jew Alice Schaper nee Rohr, who took piano lessons from Bruno, claimed, "We all knew he was Jewish. ...He looked just like a typical Jew." In town, Bruno was called Isidor Suess behind his back. With such rumors going around, it was not surprising that Heydrich felt continually burdened by these allegations, especially when he served as an SS general.

One will never know whether Heydrich was truly of Jewish descent unless more documents are found, but it is possible that Himmler and Hitler may have believed he was. In the early 1930s, according to Himmler's masseur Felix Kersten (if he can be believed), Hitler had told Himmler, "Heydrich was a highly gifted but also dangerous man, whose gifts the movement had to retain. Such people could still be used so long as they were kept well in hand and for that purpose his non-Aryan origins were extremely useful; for he would be eternally grateful to us that we had kept him and not expelled him and would obey blindly."

According to Speer, Hitler often used flaws of men in positions of authority to control them. In this case, Heydrich's possible flaw was "Jewish ancestors." Heydrich often took those who claimed he was Jewish to court for slander. He did so as late as 1940 and sent another man to a concentration camp. Admiral Canaris, head of the Abwehr, presumably had a large dossier on Heydrich's Jewish past and threatened to reveal what he had if the SS tried to infringe on Abwehr activities. Heydrich was definitely haunted by stories of his Jewish past.

Hitler's actions with Rohm and Heydrich show that he had the ability to ignore "defects" in men who, he felt, could serve his political cause. In this respect, Hitler bent his ideological principles to meet political needs.

This article is excerpted from Mr. Rigg's book with permission of the publisher.