(CNN) Eastern Virginia Medical School has promised an investigation into all past yearbooks in the wake of the controversy surrounding the state's Gov. Ralph Northam.

A racist photograph, which was obtained by CNN, appears in the medical school's 1984 yearbook and shows one person dressed in blackface and another in the KKK's signature white hood and robes. Northam, on Friday, confirmed he was one of the people pictured and issued an apology, calling the costumes "clearly racist and offensive." But on Saturday, he said he does not believe he is either person in the photograph.

Eastern Virginia Medical School President Richard V. Homan said in a statement Saturday he would call for an external investigation "to review all of our past yearbooks, determine the processes for publishing those yearbooks; discover what, if any, administrative oversight was exercised; examine our campus culture; and provide recommendations for future actions."

Homan said the panel for the investigation will include "advocates for diversity and inclusion representative of our greater community, including African Americans and other people of color."

"We commit to transparency and moving the investigation forward as quickly as possible," he said.

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