NORFOLK — A three-month investigation into a racist picture on Gov. Ralph Northam’s 1984 medical school yearbook page wrapped up with a central mystery unsolved, as investigators announced Wednesday that they have not determined if the governor is in the photo.

The lingering question could cast a shadow over the Democrat, who defied widespread calls for his resignation when the photo surfaced in February. He has vowed to serve out the remaining two and a half years of his term, devoting himself to the cause of racial equity.

After interviewing former classmates, including several who worked on the yearbook staff, investigators said they could not conclusively determine whether Northam was in the photograph, which depicted one person in blackface and another in Ku Klux Klan garb at what appeared to be a costume party.

“With respect to the photograph on Governor Northam’s personal page, we could not conclusively determine the identity of either individual depicted in the photograph,” said the report commissioned by Eastern Virginia Medical School. “The governor himself has made inconsistent public statements in this regard. No individual that we interviewed has told us from personal knowledge the governor is in the photograph, and no individual with knowledge has come forward to us to report that the governor is in the photograph.”

EVMS released the findings at a Wednesday morning news conference on its Norfolk campus with its president and provost, Richard V. Homan, and McGuireWoods partners Richard Cullen and George Martin.

The probe was headed by Cullen, a senior partner a former Virginia attorney general and former U.S. attorney for the Eastern District of Virginia.

The 36-page report, with 16 pages of exhibits, included a footnote that said, “We acknowledge there is scant information on this subject thirty-five years after the fact. Memories fad over such a lengthy time period and we were unable to contact some individuals who may have relevant knowledge.”

Investigators said they could not determine if the photograph was placed on Northam’s page by mistake or without his knowledge.

“...We sought to determine whether there is information that the photograph was placed on his personal page in error or by any other means not at his direction. Our inquiry in this regard was restricted by the passage of time and the dearth of contemporaneous documentation. was placed on his personal page in error or by any other means not at his direction. Our inquiry in this regard was restricted by the passage of time and the dearth of contemporaneous documentation. While we have identified no information that the photograph was placed on Governor Northam’s personal page in error or by any other means not at his direction, we could not conclusively determine the origin of the photograph.”

Hours after the photo surfaced on a conservative web site on Feb. 1, Northam apologized for appearing in it. National Democrats — led by 2020 contenders — swiftly called on him to step down, and before the night was over, even home-state allies had joined in.

But at a news conference the next day, Northam denied he was in the picture and said he had no idea how it ended up on his personal page. He said he had never purchased the yearbook and had never before seen the photo.

However, Northam did admit to wearing blackface to imitate Michael Jackson for a 1984 dance contest. That disclosure, along with his about-face on the photo, only intensified calls for his resignation.

He refused, saying he would solve the mystery of the photo, perhaps with help from a private investigator or facial recognition software.

Amid the turmoil, the medical school hired the McGuireWoods law firm to review the publication of the photo on Northam’s yearbook page and any other yearbooks with offensive material, as well as the school’s culture pertaining to race. The school banned yearbooks in 2014.

The report released Wednesday said that photographs of individuals in blackface were not isolated to the 1984 EVMS yearbook. In a review of year books spanning from 1976 through 2013, there were at least 10 photographs that included individuals in blackface. The last incident occurred in 2004.

Northam, a well-liked former lieutenant governor and state senator, was hit by the blackface scandal just as he’d wrapped up a consequential first year in office.

Working with Republicans, he’d expanded Medicaid to 400,000 low-income residents, struck a bipartisan deal for criminal justice reform and permanent funding for Metro, and landed the biggest economic development coup in recent history: Amazon’s decision to locate its second national headquarters in Arlington.

The first major controversy of his administration exploded in late January, as he discussed late-term abortion a radio show in a way that Republicans, including President Trump, called an endorsement of infanticide. A pediatric neurologist, Northam called the infanticide charge “disgusting.”

Days after the radio remarks, the racist photo from his yearbook surfaced onthe Big League Politics website — supplied by someone offended by Northam’s abortion comments, staff with the site have said.

When first confronted with the photo, Northam was confused and stunned by the swift condemnation, those close to him have said. President of the Honor Court during his senior year at Virginia Military Institute, he felt compelled to take responsibility for the picture because it was on his page, according to these people, who spoke on condition of anonymity in order to discuss private deliberations.

“I am deeply sorry for the decision I made to appear as I did in this photo and for the hurt that decision caused then and now,” he said in a written apology.

But later that night, he said he didn’t remember dressing that way and became convinced that the image wasn’t of him, these people said. The prospect of resigning in shame over something he did not do was unpalatable to him, they said.

As he sought to hang on, new scandals rocked the Capitol, shifting the spotlight to the two men in line to succeed Northam. Attorney General Mark Herring (D), who’d called on Northam to step down, admitted that he also had worn blackface, at a college party when he was 19. And Lt. Gov. Justin Fairfax (D) faced allegations from two women who said he sexually assaulted them in the early 2000s, which he disputes.

The trio of controversies could hurt Democrats in an election year when all 140 seats in the General Assembly are on the ballot this fall. Fundraising has dropped off sharply for all three. And Republicans, who are trying to hold onto narrow control of the state House and Senate, continue to slam “Gov. Blackface.”

But as time has passed, Northam has resumed public appearances, albeit cautiously. Some Democratic lawmakers have been appearing publicly with the governor, particularly when he is advancing a cause that promotes racial equity. Some think they were too hasty when they called for Northam’s resignation, although their caucuses have stood by calls for him to resign.

First elected to the state Senate from Norfolk in 2007, Northam was courted by Republicans because of some conservative leanings, and was identified early by now-Sen. Tim Kaine (D), who was then governor, as gubernatorial material because of his experience in both health care and the military. Northam served in the Army for eight years after medical school and treated soldiers wounded in the Persian Gulf War.

After serving as McAuliffe’s lieutenant governor, Northam ran for governor in 2017. During the campaign, he paid special attention to black churches, often attending two or three on Sundays. His home pastor is African American. After the racial violence in Charlottesville that summer, Northam was among the first Virginia political figures to react, making an emotional plea for all Confederate monuments to come down.

He later walked that back and now says it should be up to localities, but he said recently that his personal belief is that such statues are harmful.