There is a whiff of Indiana Jones in the career of Dr. Dovid Katz.

Not that the Yiddish professor who will be speaking in Teaneck on Sunday night has braved gun fights, jumped from car to car, or mastered the bullwhip. But in an academic field prone to bookishness, Dr. Katz has embarked on scholarship enmeshed with real world investigations, exotic travel, and, yes, battles with real-life Nazis, or at least their sympathizers.

It is, after all, one thing to study and teach Yiddish professionally, or even to earn a position at Oxford and a visiting professorship at Yale. It’s another thing to settle in Vilnius, the capital of Lithuania formerly known as Vilna, as Dr. Katz did in 1999. His mission was the linguistic equivalent of Indiana Jones’ archeology: To map the nuance of Yiddish usage as it varied from village to village by speaking to its last surviving native speakers.

And it is one thing to talk about preserving the memory of the Holocaust. It is another to be fired from your job for defending the uniqueness of the Nazi genocide against fascist apologists.

Dovid Katz was born in Brooklyn in 1956. His father, Menke Katz, was a poet whose 1938 Yiddish masterpiece, “Burning Village,” recounted his transition from his town near Vilna to the Lower East Side.

In some ways, the elder Katz’s move to the New World was more successful than most: He matched his nine award-winning volumes of Yiddish poetry with nine volumes of English poetry, which also won awards. He was a successful editor of the literary journal “Bitter Roots.”

But for his son Dovid, Menke tried to create a life rooted in the Lithuanian shtetl. “He brought me up entirely in Yiddish as a matter of principle,” Dovid Katz said.

“It was a very happy childhood. My father created an imaginary world for me of the exotic characters of his shtetl. The semi-mythical world I had was much more interesting than the gray boring streets of Brooklyn.”

As Dr. Katz grew older, the reality of Brooklyn remained pale compared to the tales of the Old World. “Our street had the whole spectrum, from chasidic to Jewish communist,” he said. “A fascinating variety of European Judaism was still there, in the old generation, when I was a kid. There were very many European Jews and survivors with fantastically different stories.” When he was a teenager, the neighborhood grew more chasidic. “Although by and large in those years the charedim of Borough Park were not particularly friendly to our family, I developed a number of lifelong friendships,” he said.

Perhaps it was natural that when it was time for college, Dr. Katz would study linguistics at Columbia, the rare American university that taught Yiddish. Yiddish, after all, was his homeland; Brooklyn was just a place he and the other children of displaced immigrants were passing through. “Every one of my friends wanted to leave. Not one of my closest circle is now in Brooklyn or even New York,” he said.

If there were all kinds of Jews in his corner of Brooklyn, there also were all kinds of Yiddish. There was the Lithuanian Yiddish of his family, and then “the Galizianer, the Ukranian, the Polish Yiddish around us.” The different dialects are “very different sounding, but completely the same written language. It’s like a lock being turned one notch for every vowel.

Dovid Katz and Shimon Alperovich, head of the Jewish community in Lithuania.

Dovid Katz and Shimon Alperovich, head of the Jewish community in Lithuania.

“Because the differences are systematic, once the initial hilarity of one dialect hearing the other is past, you understand everything,” he said.

The sounds are the first clue to a dialect’s difference.

“Going deeper, it’s syntax, words,” he said.

Those familiar with the nuances can tell the differences between a text written in Lithuanian Yiddish by a Lubavitcher rebbe and those in Galizianer Yiddish by a Satmar rebbe.

Dr. Katz has written books about the broad history of Yiddish, its linguistic and cultural evolution in the thousand years of European Jewry. His specialty, though, is the history, nuance, and variations within Lithuanian Yiddish.

Lithuania, in Yiddish terms, “is much bigger than today’s Lithuania,” he said. “It includes Latvia, all of Belarus, northeastern and eastern Ukraine, northeast Poland, and westernmost Russia.” In other words, pretty much what the Duchy of Lithuania ruled at its peak in the 15th century.

And within that Lithuanian Yiddish, “there are vast internal differences. The more you study, the more you see it’s not monolithic.”

It was not just a question of dialect; it was also a matter of culture and religion. The east was mostly chasidic, including the ancestors of present-day Chabad. The west was mitnagid, non-chassidic, the world of yeshivas and intense Talmud study.

One of Dr. Katz’s major projects is a linguistic map of Lithuanian Yiddish. “You can divide up the territory with any word that differs,” he said. “The word ‘ear’ would be ‘ever’ in Minsk, ‘eyver’ in Vilna, ‘eyer’ in Kovno, and ‘euer’ in Koenigsberg.

“There are many cultural interactions and differences. The ones in the West were closer to German culture. The ones in the Far East to Russian culture. The ones in the middle to Polish culture,” he said.

Finding the details of the variations was the work of his interviews: roughly 3,000 over 25 years, starting in 1990. The oldest person he recorded was born in 1897. “I wanted people who remembered something of the pre-World War I era,” he said.

He would go to villages and ask for the oldest Yiddish speaker. “When I started, I wouldn’t speak to anyone born in 1920. I said I’d catch them next year.”

It was cultural archeology, trying to get back as far as possible. “If I interviewed someone who remembered her grandparent’s culture and folklore, it was going back two hundred years,” he said.

Of all the varieties of Yiddish, “Lithuanian Yiddish is now in the greatest danger of extinction,” he said. The chasidim who speak Yiddish in Borough Park and beyond keep the language alive, but they speak other dialects.

Beside his historical working in mapping the dialect, Dr. Katz has made original cultural contributions to Yiddish. He has written three volumes of fiction. And he has begun translating the Bible into his beloved dialect.

“If I live long enough, I’ll write the whole Tanach,” he said. “It’s my little contribution to the preservation of Lithuanian Yiddish for the generations to come, for the select few who are interested in such things.”

The focus on the internal variations of Yiddish is a departure from the work of Yiddishists a century ago. Then, in the face of critics who denied that Yiddish was a real language, the focus was on standardization, creating a single version to unite European Jewry. The result, which is what is now taught in universities as standard Yiddish, “tends to be a very sterile, lowest common denominator form that’s often very watered down, bereft of deep Hebraic and Yiddish roots. I think it’s over-standardized.”

Lithuanian ultranationalists march in Kaunas on February 16, 2015. (Cnaan Liphshiz)

Lithuanian ultranationalists march in Kaunas on February 16, 2015. (Cnaan Liphshiz)

Standard Yiddish, he said, “should be an entrance to the real product rather than a replacement. When a student hears the real McCoy Yiddish of someone born in Kovna or Vilna, it’s very important that the student feel comfortable with that as well.”

And yes, he’s posting the tapes from his fieldwork on YouTube, so the Yiddish he captured can be heard by students.

Dr. Katz has an encouraging message for potential Yiddish students: “It’s not particularly difficult” to learn the language. “It’s much easier than Hebrew. Very many of the roots are European. There are very many cognates with English.

“Its been a sociological issue, whether people want to learn it or not,” he said.

(Back in his high school days at the Yeshiva of Flatbush, he fought the battle with a protest calling for Yiddish to enter the day school curriculum.)

That’s the linguistic side of Dr. Katz.

As for politics — that concerns “the very history of the Holocaust,” he said. “There is an Eastern European effort to rewrite the history of the Holocaust, to write it out of history without denying a single death.”

What he calls “the new Holocaust denial” takes the form of “double genocide” theory.

“Yes, the Holocaust happened, but it was only one of two equal genocides,” is how he summarizes the argument. “First came the Russians and the Jews, and they committed genocide against us,” the Eastern Europeans, who are making this argument. Then came the Germans and us, who committed genocide against the Jews.” In other words, the new deniers admit that their ancestors committed genocide against the Jews, but say that they were pushed to it by the Jews, who did it first.

Another claim, enshrined by law in Lithuania and other countries, is that Soviet and Nazi crimes are equal. That claim has victimized elderly Holocaust survivors directly.

That’s how Dr. Katz first became involved. He defended three Jews who had fought with Soviet partisans against the Nazis in the 1940s, and whom Lithuanian prosecutors had accused of war crimes in 2008.

“Promoters of the double genocide theory have to claim that Jews were also war criminals,” he said. “That’s why they had to find Jews who were part of the Soviet partisans and say they are war criminals. They’ve only picked on Jewish partisans.”

“History that is simple and clear is being made into a big muddle on purpose. They don’t want the stain of the Holocaust on them.”

This anti-Semitism comes from right wing eastern Europeans. That position has been ascendant in countries like Lithuania and Hungary for the last few years. Beside going after Jews for alleged Soviet genocide, right-wing politicians also are trying to rehabilitate pro-Nazi governments as heroes because they were anti-Soviet.

“In 2012, the Lithuanian government reburied the Nazi puppet prime minister with full honors,” Dr. Katz said. “Murderers are being made into heroes.”

At the beginning of World War II, Jews were murdered on the eastern front, with the cooperation of locals in Lithuania, Latvia, Belarus, and the Ukraine. That collaboration had major ramifications.

“The bulk of the murders occurred by shooting, starting in June 1941 with the Nazi invasion of the Soviet Union,” Dr. Katz said. “Nationalists who are today being revered as heroes began to murder Jews even before the first German soldiers arrived. Only after that did Hitler decide on genocide at Wannsee in January 1942, when he saw how easy it would be to get volunteers to shoot all the Jews and bury them in a pit outside of town. After that concentration camps became death camps. The gleeful participation in the actual killings in the Baltics and Ukraine is a sharp contrast to the history in Poland and Hungary.

“The double genocide theory is intended to let all of the Eastern European countries off of the hook.”

Dr. Katz accuses the Eastern European governments’ investment in Jewish studies and Holocaust education as being “a cover for their revisions.” The American government has been reluctant to criticize its Eastern European allies, he said.

“There were big neo-Nazi marches featuring big banners of Holocaust perpetrators. I don’t know why the American ambassador couldn’t have made a polite statement of disapproval.

And most American Jewish organizations, he charges, have traded access for silence, and have looked away.

He has been chronicling this history at defendinghistory.com, where you can also find his Yiddish work, including the Bible translations.

“I’m often made fun of, called ‘Dovid Quixote,’” he said. “That’s fine with me. I’m not going to defeat any government. I’m proud we have provided a daily record since 2008 of what’s going on, a record that’s important for future historians. History will sort out the truth, as always.”

So what’s it like to be a Jew speaking out against the government in Lithuania today?

“It’s a bit weird,” he said.

“I have many, many friends. I’ve found the people to be friendly, warm, tolerant. I’m very close to the survivor community. My friends are Yiddish-speaking Jews in their 70s, 80s, and 90s. And I have a young circle of friends of different backgrounds.”

Most people in Lithuania are not anti-Semitic, he said. “This is a problem of the elite, and of the far right, the neo-Nazis, who are in cahoots.

“On the negative side, I lost my job and career.”

Dr. Katz said that his bosses at Vilnius University warned him to stop lobbying in defense of the Jewish partisans. When he didn’t, he was fired. His supervisor at the university denied Dr. Katz’s version of his story in an interview with JTA last year. JTA noted that the supervisor was a member of Lithuania’s commission on Nazi and Soviet crimes.

“It’s a very big blow not to have monthly income,” Dr. Katz said. “The second thing is I’ve been followed by government agencies. The third is I’ve been followed around by the neo-Nazis who publish unflattering pictures of me. I have no secrets. I’m an old bachelor with no secrets. And the anti-Semitism in Eastern Europe has, so far, been completely nonviolent.

“There is a price to pay, of course. To be regarded as an opponent of the state. I’m often called a Russian spy. There is abuse that way and you get used to it.

“If you’re committed to your belief in the truth, you have your life.”

Save the date

When: Sunday, April 10, 8 p.m.

Where: Congregation Rinat Yisrael, Teaneck

What: Professor Dovid Katz discusses Six Hundred Years of Conflict: the Tumultuous History of the Yiddish Language.”