Charles Koch, head of Koch Industries, talks about his new book on Market Based Management on Feb. 26, 2007.
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Updated: January 14, 2016 6:13 PM ET | Originally published: January 14, 2016 4:29 PM EST

A senior Koch Industries executive is disputing a new book that says Fred Koch, the father of billionaire brothers Charles and David Koch, helped build a Nazi oil refinery.

In the letter to company employees, David Robertson, president and COO of Koch Industries, said Fred Koch’s work for the Nazi regime was one of many international projects and predated World War II, according to the New York Times.

“To cherry-pick one project among hundreds during this time frame and then use it out of context in order to further an agenda-driven story line is grossly inaccurate,” Robertson said.

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In Dark Money, a new book about the political influence of some of the country’s wealthiest families, New Yorker staffer Jane Mayer writes that one of Koch’s projects was a major oil refinery for Nazi Germany, which Adolf Hitler personally approved, according to the book.

Mayer has defended the book’s accuracy.

“As the Kochs are confirming, Fred Koch was integrally involved in the creation of a German refinery that Adolf Hitler personally greenlighted. Splitting-hairs by disaggregating which parts of the equipment Fred Koch provided is a distraction,” she said in a statement. “Without the cracking unit, which Fred Koch designed, there would be no refinery.”

Koch Industries and the Koch brothers, known for funding conservative political candidates, have previously criticized Mayer’s reporting on their family.

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Write to Katie Reilly at Katie.Reilly@time.com.

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