(CNN) As Virginia's governor struggles to explain how a racist photo ended up on his personal yearbook page, a yearbook staff member said each student had control over such pictures.
Dr. William Elwood worked with others on the layout for Eastern Virginia Medical School's 1984 yearbook -- the same yearbook that featured a photo of a person in blackface and another person in a Ku Klux Klan outfit on Ralph Northam's personal page.
Elwood said photos for personal pages "were chosen by the individual student."
"They were submitted in a sealed envelope with their name on it to the yearbook staff, to be put on their page," Elwood told CNN.
"The pictures for the personal ones were not just chosen at random from other pictures that might have been available at that time."
Elwood said it's possible someone other than Northam submitted the disturbing photo, but it seems unlikely.
"Anything is possible, but the probability is low unless someone was out to get him and was able to get access to all this stuff," he said. "All of this stuff was kept in a locked room, and the only time the room was unlocked was when somebody was in that room working on the yearbook."
He also said it's unlikely that staff members mixed up photos during production because "as far as I know, nobody complained that their picture was under the wrong person."
After Northam's yearbook page surfaced last week, the governor said Friday that he was one of the two people in the photo.
But the next day, he said he was not in the picture -- though he admitted he appeared in blackface at another time that same year, dressed as Michael Jackson at a San Antonio dance competition.
Northam has said he's not sure how the racist photo ended up on his yearbook page. The governor said he never bought the book and wasn't aware the offensive picture was on his page.
When asked who reviewed the yearbook before publication, Elwood said "the editor looked at everything before it went to the publisher. I don't know what faculty oversight there was, but definitely if there had of been a problem with it then then they would have said something and probably removed it."
In light of the controversy, Eastern Virginia Medical School said it will investigate all past yearbooks.
Elwood said he didn't know Northam very well when they were in med school. He said neither the governor nor his office has reached out to him since the yearbook controversy surfaced.
Despite widespread calls for Northam's resignation -- including from fellow Democrats -- the governor said he's not stepping down.