Republican presidential candidate Donald Trump, who has been under fire for controversial statements since he launched his campaign in early June, was accused of perhaps the most outrageous act of all, mocking a person’s physical disability.

Trump recently said that he watched “thousands” of people on television, presumably of Arab descent, in Northern New Jersey on September 11, 2001 laughing and celebrating at the attacks on the World Trade Center across the river that day.  Many in the media quickly denounced that statement as an Internet hoax, and the Washington Post’s factchecker gave Trump four out of four “Pinocchios” for lying.

Within minutes, the Post’s factchecher was factchecked, as reports surfaced that the source of the original story was none other than the Post itself. On September 18, 2001, a week after the attacks, then-Post columnist Serge Kovaleski wrote that law enforcement officials were interrogating people “allegedly seen celebrating on rooftops” in a “tailgate party” manner, as they watched the devastation in lower Manhattan from afar.

Kovaleski, now a writer for the New York Times, who suffers from arthrogryposis, a condition that affects joint movement, said there weren’t “thousands” (implying that there were indeed some), bu says he doesn’t really recall.

In response at a rally, Trump said of Kovaleski: “The story was written by a nice reporter. Poor guy. You’ve got to see this guy: [flailing his arms] ‘Err, I don’t know…'”  The implication of Trump’s combined verbalization and non-verbal actions was that he was imitating Kovaleski’s disability.

The Times lashed out at Trump in response, and Kovaleski himself, who said he met with Trump several times in the 1980s and 1990s, described Trump’s action a predictably “low rent” thing for him to do.

Trump strongly denied that he was imitating Kovaleski’s condition, and lashed out at the Times and Kovealeski himself for grandstanding. Saying he has “one of the all-time great memories,” Trump nonetheless said he does not remember who Kovaleski is, nor whether he has a physical disability or is in great physical shape, like Muhammad Ali in his prime.

In a statement released by his campaign on Thanskgiving Day, Trump said: “Serge Kovaleski must think a lot of himself if he thinks I remember him from decades ago, if I ever met him at all, which I doubt I did. He should stop using his disability to grandstand and get back to reporting for a paper that is rapidly going down the tubes.”