LEFT: Officers of the Hi-Y club in the 1977 Onancock High School yearbook. Ralph Northam is standing in the back row in a checked shirt. Terry Smoot, far right, is wearing plaid pants. RIGHT: A photo from Northam’s 1984 medical school yearbook page shows two people, one in blackface and one in a Ku Klux Klan robe and hood. The person in blackface is also wearing plaid pants. Smoot says it isn’t him. (Obtained by The Washington Post)

Call it the Plaid Pants Theory.

The furor over the now-infamous photo on Virginia Gov. Ralph Northam’s yearbook page — of one person in blackface and another in a Klan robe and hood — has led Internet sleuths to another photo, from Northam’s high school yearbook in 1977. It shows Northam and four other student officers from the Hi-Y club, a civic organization in which Northam served as president.

In the black-and-white photo, Terry Smoot, the club secretary, is wearing loud plaid pants typical of the late 1970s.

The pants are very similar, those examining them on social media note, to the pants worn by the person in blackface in the photo on Northam’s 1984 medical school yearbook page.

The governor denies that the blackface photo is his but has been unable to explain so far who is posing in the photo and how it got into his medical school yearbook.

Searching for an answer to that question, people using Google this week had begun to type in “Northam and Plaid Pants Theory.” But it was really two opposing theories.

The governor’s critics saw the pants as proof that Northam must have been involved.

“Smoking gun?” wrote one under the Twitter handle @CafeNetAmerica. “Photo shows Man in Same Plaid Pants as the Blackface-KKK Yearbook Photo.”

“Unless guys in 1984 shared pants, the one in blackface in #Northam picture is NOT @GovernorVA,” countered @HillBuzz, who posited that the governor might be the one donning the KKK hood.

Others focused on height: Northam is taller than Smoot in the high school photo, and the person in blackface is taller than the person in the Klan robe in the medical school yearbook. So if Smoot is the person in blackface, then neither person in the picture could be Northam, this theory goes.

There’s just one problem. The guy in blackface?

“It definitely is not me,” Smoot told The Washington Post in a phone interview on Tuesday.

Smoot, who lives outside Richmond, remembers the pants from high school. But he says he lost contact with Northam at about that time.

The two went to different colleges and never hung out or went to parties together in the years after, and Smoot says he definitely was never present when someone wearing his pants — or ones like them — dressed in blackface.

Smoot, 60, said he was flabbergasted to see the photo from Northam’s medical school yearbook surface over the weekend — and shocked even more in subsequent days to find reporters knocking on his door and calling his and his family members’ phones.

“I’ve now looked up the websites. I’ve seen my face superimposed on the other person in costume. And I’ve read the analysis of how the pants hang on my frame, and, to be honest, I find it all rather absurd,” Smoot said.

Smoot said he barely remembers the Hi-Y club, but he does remember the governor. He said he can’t imagine Northam ever having dressed as either person in costume featured some seven years later on his page in the Eastern Virginia Medical School yearbook.

“From my knowledge of Ralph, he’s an honest fellow, and there’s not a racist bone in his body. The whole notion of him dressing like that is just so foreign, I couldn’t believe it was him,” Smoot said. “There were other people I could suspect of doing something like that, but not Ralph — he was too well liked by everyone.”