His adviser approved, he recalled, and as he was leaving the building following their meeting an acquaintance reminded him that “the Jews were involved in civil rights before it became a Negro issue,” he would later write. Another friend suggested that the topic be narrowed further to Leo Frank.

Image Professor Dinnerstein in 1998. He concluded in his scholarly work that anti-Semitism had become “an irrevocable part of the American heritage.” Credit... University of Arizona

“My response was, ‘Who’s Leo Frank?’ ” Professor Dinnerstein recounted.

He went on to research and write about Frank, who ran a pencil factory and was sentenced to death for the strangling in 1913 of Mary Phagan, a 13-year-old employee. After the governor commuted the sentence to life imprisonment, a mob kidnapped Frank and hanged him.

No one was prosecuted for the lynching. As a result, and because the state had failed to protect Frank so that he could pursue legal appeals, he was posthumously pardoned in 1986 by the Georgia Board of Pardons and Paroles, although not officially absolved of the crime itself.

Professor Dinnerstein’s thesis was published in 1968 by Columbia University Press, titled simply “The Leo Frank Case.” It has never been out of print.

“The book launched my professional academic career in 1968,” he wrote in the preface to a 2008 revised edition, which added an up-to-date perspective to the original exploration of what Professor Dinnerstein described as “the ambivalence that Southerners felt toward Jews” and “the poor judgments that some Jews made when trying to defend Frank.”