More than a year after it was revealed that Volkswagen used illegal "defeat device" software in diesel cars to cheat on emissions tests, the company is still working to rebuild its reputation.

Another crisis and ensuing public criticism is the last thing VW needs right now.

But opaque statements and the effect of German labor laws may have combined to produce any potential scandal, which surfaced last week—far from the topic of diesel emissions.

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What happened as Volkswagen parted ways with a historian who helped chronicle its connection to Germany's World War II Nazi government has generated controversy, reports The New York Times.

In an open letter, 75 prominent German historians accused Volkswagen of vindictively terminating the contract of historian Manfred Grieger.

Neither party has openly discussed the reasons for the split—or whether he was in fact dismissed.

Volkswagen plant

Volkswagen plant

In part, that may be due to highly restrictive German labor laws governing what a company may and may not say about its employees and their actions.

According to The Times, the catalyst for Grieger's departure seems to have been a critical review he wrote last year of a study of World War II labor practices of Volkswagen subsidiary Audi (more likely its predecessor Auto Union).

In his review, Grieger criticized the authors for allegedly downplaying the company's cooperation with the Nazis and its use of forced labor.

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Neither the review nor the study—which was published in 2014—reportedly received much attention until late August, when they were mentioned in the German business weekly Wirtschaftswoche.

The review led to "talk that Grieger be put on a short leash and limited in his academic freedom," according to the open letter from the historians. This in turn led Grieger to leave, it said.

The historians also expressed concern that Grieger's departure will signal the end of VW Group's transparency about its past, including allegations of collaboration with the military dictatorship in Brazil during the 1970s.

Volkswagen plant, Wolfsburg, Germany

Volkswagen plant, Wolfsburg, Germany

A Volkswagen statement released Thursday said the Brazil inquiry will go ahead.

Prior to Grieger's departure, the Volkswagen brand had a reputation for being among the most transparent of German companies when it came to its World War II past.

Grieger was the co-author of an exhaustive study published in 1996—totaling more than 1,000 pages—that exposed Volkswagen's use of forced labor during the war.

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It also detailed the use of the company's main Wolfsburg factory in making war materiel, and the complicity of members of the Porsche and Piëch families—who together still wield enormous influence over VW today.

After the study was published, Grieger oversaw the Volkswagen company archives, making them freely available to researchers and journalists.

That openness was not replicated in the tight-lipped response by its German communications unit to the diesel scandal—a response that only exacerbated the situation as VW Group attempted to do damage control even as the scandal ballooned.

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