Carson related the tale in his 1990 book "Gifted Hands." He wrote that he showed up to retake an exam for a psychology course, which he said was titled "Perceptions 301," after the original tests were "inadvertently burned." The retired neurosurgeon claimed in the book that all 150 students who showed up for the makeup test walked out except for him. In Carson's telling, the professor then told him the makeup test was a hoax designed "to see who was the most honest student in the class." The professor then handed him $10 and a photographer from the Yale Daily News took his photo, according to Carson's book.

Late last week, however, the Journal identified several holes in that story. A search of the Yale Daily News archives turned up no photo of Carson. A Yale librarian also told the newspaper that there was no psychology class called "Perceptions 301" offered at the university while Carson was a student there.

Now here's where it gets interesting (read: complicated).

Carson launched a counteroffensive Sunday on his Facebook page, where he posted a link to a syllabus for a psychology course called "Perception" that Yale offered in 2002 as evidence that the class he referred to did exist when he attended in the early 1970s. He also posted a contemporaneous article from the Yale Daily News that he said proves his version of the story. The article, dated January 14, 1970, explained that Yale's humor magazine, The Yale Record, had printed a parody issue of the News the day before that included a notice about the makeup psychology exams.

"The magazine also announced in the substitute NEWS that a series of Psychology 10 exams were destroyed and stated that a makeup would be held at 7:30 last evening," the article read. "A false exam held in 203 WLH was attended by several students not aware that the replacement exam was a hoax. The exams distributed to the group closely resembled the psychology exam given on Monday morning."

As the WSJ pointed out, the date on the Yale Daily News article corresponds with Carson's freshman year at Yale, not his junior year. The article states that "several," not 150, students showed up for the makeup exam. There's also no mention of a professor participating in the "hoax."

Still, Carson's campaign manager stood by the candidate's story.

"The story as he presented it is true. A couple of the details are fuzzy,” campaign manager Barry Bennett told the WSJ in a Sunday interview.

Carson himself appeared to concede that some details in the "hoax" exam story were embellished during an interview with ABC's George Stephanopoulos.

“You know, when you write a book with a co-writer and you say that there was a class, a lot of time they’ll put a number or something just to give it more meat,” Carson said on ABC's "This Week." “You know, obviously, decades later, I’m not going to remember the course number.”

An assistant to Carson’s “Gifted Hands” co-author Cecil Murphey, Twila Belk, told TPM on Monday morning that Murphey was declining all interviews about Carson.

It's possible that Carson's photo never appeared in The Yale Daily News because the "hoax" makeup exams were administered as part of a prank by The Yale Record. But even though the retired neurosurgeon posted a News article that clearly outlined the prank, he didn't say he got duped. Instead, he stood by the veracity of his version of events as opposed to the WSJ's.

"Will an apology be coming. I doubt it," he wrote on Facebook.