The prominent Polish-born American historian Jan Tomasz Gross, who revealed the crimes committed by Poles against the Jews during the Holocaust, is gearing up for a legal battle over the “historical truth” against Polish authorities who, it now turns out, are still considering putting him on trial for harming Poland’s reputation.

In a surprise move in October, the Polish public prosecutor general decided to reconsider closing the investigation of Gross and instead to pursue it further until a final decision is made on whether to charge him. Conviction would carry a maximum penalty of three years in prison.

“It’s very disturbing. It’s political. I don’t believe that court is the place where historical issues having to do with Polish-Jewish relations during the war should be debated,” Gross told Haaretz over the weekend from his home in the United States.

The investigation against him was opened several months ago following an article that Gross wrote in which he noted the large extent to which Jews were murdered by Poles during World War II. Gross wrote that the figure was larger than the number of Germans killed by Poles. “Consider the Poles, who, deservedly proud of their society’s anti-Nazi resistance, actually killed more Jews than Germans during the war,” Gross wrote.

After the article appeared, the public prosecutor general’s office reported receiving a large number of complaints about what Gross had written, from people who demanded that he be charged with harming Poland’s reputation.

“They got angry that a crazy guy like me writes something which is so banal that anybody who is a historian of that period and knows anything will tell you,” Gross told Haaretz. “I wanted to bring to people’s mind the enormity of the crimes made by Polish fellow citizens against Jews. This is unfortunately the case. Poles killed a maximum 30,000 Germans and between 100,000 to 200,000 Jews.”

Fifteen years ago, Gross attracted widespread international attention with the publication of his book “Neighbors,” in which he described the murder of hundreds of Jews at the hands of their Polish neighbors in the Polish town of Jedwabne in 1941. “Things happened not only in Jedwabne,” Gross noted over the weekend, underlining the scope of the phenomenon. His critics, however, accuse him of distorting the data and seek to point out that thousands of Poles risked their own lives to save Jews.

This dispute over history, however, has landed at the offices of Poland’s public prosecutor general at a time when Poland is governed by a right-wing conservative government that was elected last year. In October, the prosecutor’s office announced that it would seek out the professional opinions of other historians with regard to Gross’ claims before deciding whether to file charges against Gross.

Among those being consulted is Poland’s Institute of National Remembrance, a government research institution whose leaders have in the past claimed that the murder of the Jews in Jedwabne was committed by Germans and not Poles.

“This is false, a lie about history,” Gross told Haaretz. “I will correct this. I’ll say how things happened not only in Jedwabne but [elsewhere]. I’ll bring people to testify,” he said in anticipation of the possibility that charges will be filed. “I stand by my work. It’s all documented very well.”

Gross points an accusing finger at the Polish government, raising the prospect that it is behind the decision to continue to pursue the investigation against him. “This strange regime works very hard on falsification of history,” he said, “and now they want to falsify the history of Polish-Jewish relations in the war.”

This year, Gross noted, the government announced that it would be drafting a law that would provide for jail time for anyone who accused Poles of responsibility for Nazi crimes.

The case against Gross is in addition to another investigation being pursued against him in Poland. The office of Polish President Andrzej Duda announced several months ago that, after receiving a large number of complaints from Polish citizens, it was considering stripping Gross of an honorary degree that he had received for his special contribution through his work for Poland.