A top foreign policy adviser to Republican nominee Donald Trump is fighting back against accusations that he made anti-Semitic remarks about the Holocaust while serving at the Pentagon during President George W. Bush’s administration.

Joseph Schmitz is one of five foreign policy advisers picked by the Trump campaign earlier this year. When Schmitz served as inspector general of the Department of Defense during the Bush administration, he had allegedly boasted that one of his successes was in “firing the Jews,” according to complaint records obtained by McClatchy.

Schmitz also allegedly lectured an employee “on the details of concentration camps and how the ovens were too small to kill six million Jews,” wrote Daniel Meyer, who once oversaw whistleblower cases at the Pentagon, in his complaint against Schmitz. Meyer is one of three former colleagues claiming Schmitz openly offended several minority groups.

However, Schmitz said in an interview that the “allegations are completely false and defamatory.”

“I do not recall ever even hearing of any ‘allegations of anti-Semitism against [me],’ which would be preposterously false and defamatory because, among other reason(s), I am quite proud of the Jewish heritage of my wife of 38 years,” he wrote in an email statement. He later clarified that his wife’s maternal grandmother was Jewish.

“Allegations of anti-Semitism are serious and deserve serious investigation and response,” the Anti-Defamation League (ADL) said in a statement. “Candidates must ensure and convey that their advisers have the highest standards of integrity.”