Earlier this month at a German airport, what began as a disagreement with airport security ended with an American woman facing a charge of defamation for allegedly calling a federal officer a “Nazi.”

The woman, a distinguished professor at Georgetown University named C. Christine Fair, claims authorities mistreated her at Frankfurt International Airport — they patted down her breasts, called her a hippie and threatened to arrest her if she lodged a formal complaint against the officers — before fabricating the allegation against her.

“This was the most extraordinary case of police corruption I’ve personally witnessed,” she told The Star.

In a press release issued by the airport’s public relations department, German authorities claimed the 49-year-old called them “f---ing bastards” and “f---ing German Nazi police.” They also claimed witnesses could corroborate the accusation.

But Fair said she merely muttered under her breath that while the officers were mistreating her for attempting to carry-on a toiletry item, they were ignoring the “Nazi-looking dude” in the security line.

Fair was arrested on suspicion of defamation and charged $260. She wrote in an account of the incident published by the Huffington Post that the payment was “a considerate robbery in which the perpetrators left me with a receipt.”

Police kept tabs on Fair after she left the country, monitoring her tweets and reading her Huffington Post account. Police wrote Fair “continues to insult the Federal Police officers and the security staff as ‘thugs in uniform.’ ... These insults have become evidence in the preliminary investigations.”

The incident began when Fair’s bag was flagged for possibly containing explosives. It didn’t, but the incident intensified as a disagreement broke out over whether Fair’s Speed Stick deodorant was a solid or a liquid.

The airport officers said it was a liquid and told Fair to dispose of it or transfer it to her checked luggage.

Fair argued it was a solid.

As the situation grew tense, Fair began to suspect the treatment may have been motivated by sexism.

“If I were a male, I don’t think they would have threatened me with arrest,” she said.

But authorities say Fair became “increasingly uncooperative” before saying they were “f---ing German Nazi police.”

Fair repeatedly requested that the officers review the security footage, saying it would have cleared her, proving she wasn’t directing the insult at any officer.

She was detained, and police opened a preliminary investigation for defamation. She was later allowed to continue on her travels to India.

Uttering “Nazi” has become taboo in Germany and causes swift reprimands when it is uttered “because it violates the consensus in German society about the singular nature of Nazi crimes,” USA Today reported. Manfred Heinrich of Kiel University said that while Germany has outlawed the glorification of Nazism, no law explicitly makes it illegal to call someone a Nazi.

Fair said she has contacted officials with the State Department in Germany and will meet with U.S. embassy officials in Germany.

She acknowledged, though, her own “terrible judgment” in the incident.

“I muttered it (Nazi),” she said. “I’m tired, I’m jet-lagged, already missed two flights. ... Of course it was terrible judgment that I muttered this to myself, but I didn’t call him (the police officer) a Nazi.”