A Harvard-educated fact-checker for the New Yorker is being excoriated by the Immigration and Customs Enforcement agency for “baselessly slandering” a Marine veteran — by falsely accusing him of having a Nazi tattoo, according to reports.

Officials with ICE are now demanding that the New Yorker and Talia Lavin apologize over her erroneous tweet about Justin Gaertner.

In the gaffe, Lavin allegedly implied over the weekend that Gaertner, a combat-wounded veteran and ICE forensics analyst, had the Nazis’ Iron Cross inked on his elbow.

But she deleted her post after “military veterans responded that the tattoo looked more like a Maltese cross, a symbol associated with firefighters,” ICE said in a statement.

The tattoo, according to Gaertner, is actually a “Titan 2” symbol for his platoon when he served in Afghanistan.

“The writing on his right arm is the Spartan Creed which is about protecting family and children,” ICE said. “Anyone attempting to advance their personal political opinions by baselessly slandering an American hero should be issuing public apologies to Mr. Gaertner and retractions. This includes Levin [sic] and the New Yorker.”

Gaertner lost both of his legs and suffered other permanent injuries when an IED exploded during his deployment to Helmand Province, Afghanistan. He served as a fire team leader and lead sweeper for IEDs.

Now Gaertner is a para-Olympic athlete who has “volunteered his time to motivate other wounded warriors and Boston bombing victims,” according to ICE. With the immigration agency, he helps solve criminal cases related to sexually abused children.

Lavin made her Twitter account private following the backlash over her tweet — which was in response to a May 25 ICE post that featured a photo of Gaertner.

The New Yorker issued an apology Monday that distanced itself from Lavin, according to the National Review.

“The New Yorker has just learned that a staff member erroneously made a derogatory assumption about ICE agent Justin Gaertner’s tattoo. The personal social-media accounts of staff members do not represent the magazine, and we in no way share the viewpoint expressed in this tweet,” a spokesperson said. “The tweet has been deleted, and we deeply regret any harm that this may have caused Mr. Gaertner.”

Lavin, who could not immediately be reached for comment, has made headlines before. In 2015, the then-26-year-old competed on “Jeopardy” and hilariously duped host Alek Trebek into repeating a silly “Saturday Night Live” joke mocking the game show.

Clueless as to the answer to the final question on the show, she scribbled, “What is the love ballad of turd ferguson p.s. hi mom?” — a nod to a Will Ferrell skit from 1999.