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

The lingering question could cast a long shadow over the Democrat, who defied widespread calls for his resignation when the photo resurfaced in February. He has vowed to serve out the remaining 2½ years of his term, devoting himself to the cause of racial equity.

Investigators also said they could not figure out who was responsible for placing the photo on Northam’s yearbook page.

Northam is left in political limbo — neither cleared nor convicted in a scandal that has humiliated the Gulf War veteran and pediatrician who was lauded across the aisle as a man of uncommon honor when he claimed the Executive Mansion 17 months ago.

The Republican House majority leader said the inconclusive report further wounds the governor. The report serves to remind voters of the damaged leader of the Democratic Party during a pivotal election year in Virginia, when Democrats had been hoping they would wrest control of the legislature from Republicans in November. Meanwhile, members of the Virginia Legislative Black Caucus said it changed nothing: They will continue to work with the governor but believe he should resign.

Perhaps the most striking revelation of the investigation: Officials at Eastern Virginia Medical School — including the current president and his predecessor — knew about the racist photo on Northam’s page for years but kept quiet. They opted not to tell Northam or go public, fearing they would be accused of playing politics, according to the report.

Investigators said they were hampered by the passage of time and the lack of documentation. They interviewed Northam twice, as well as his former classmates — including several who worked on the yearbook — and said they could not 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.

“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.”

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 fade over such a lengthy time period and we were unable to contact some individuals who may have relevant knowledge.”

In a statement released Wednesday, Northam insisted he was not in the picture.

“I am not in the racist and offensive photo that appears under my name in the 1984 Eastern Virginia Medical School yearbook,” the governor said. “That being said, I know and understand the events of early February and my response to them have caused hurt for many Virginians and for that, I am sorry. I felt it was important to take accountability for the photo’s presence on my page, but rather than providing clarity, I instead deepened pain and confusion.”

Northam was referring to the chaotic 24-hour period following the Feb. 1 publication of the photo by a conservative website, during which he first apologized for appearing in the picture but then called a news conference to deny it depicted him.

EVMS released the findings Wednesday at its Norfolk campus with its president and provost, Richard Homan, as well as McGuireWoods partners Richard Cullen, Benjamin Hatch and George Martin. The probe was headed by Cullen, a senior partner at the law firm and a former Virginia attorney general and U.S. attorney for the Eastern District of Virginia.

James Boyd, president of the NAACP branch in Portsmouth, Va., questioned the independence of the report, calling it a “PR blitz” to restore the reputations of Northam and the school, which he noted receives state funding.

The Republican Party of Virginia reiterated its call for Northam to step down, saying, “Virginia will not tolerate racism.” House Majority Leader Todd Gilbert (R-Shenandoah) said the failure to resolve questions about the photo leaves Northam hobbled.

“Unfortunately, this report does nothing to restore the trust that was lost, and further solidifies the uncertainty surrounding this difficult and painful event,” Gilbert said in a statement.

But Del. Lamont Bagby (D-Henrico), chairman of the Virginia Legislative Black Caucus, said it was time to move on from a seemingly unsolvable puzzle — and focus instead on addressing inequities in education, health care, housing and other areas, as Northam has pledged to do.

“It’s clear we don’t have anything conclusive. It’s evident we’ll never have that,” Bagby said. “I am less concerned with the photo and more concerned with the work we have ahead. We have 400 years worth of stuff to clean up.”

Hours after the image became public in February, national Democrats — led by 2020 contenders — called on Northam to step down. Before the night was over, even home-state allies had joined in.

When first confronted with the photo, Northam was confused and stunned by the swift condemnation, according to the report.

“I wanted to take responsibility for a picture being on my yearbook page and — I hate to say this because I’ve been in the Army and taken care of dying children — but I was shocked,” he told investigators. “It hit me like a ton of bricks. I didn’t think through it. It was rushed.”

He appeared to blame his advisers for the initial apology.

“I shouldn’t use the term raising a gun to my head, but they were saying we need to do it quickly. This is blowing up,’ ” Northam told investigators.

“There was an urgency to get the statement out. If I had to do it over again I’d do it differently,” he said. “I always rely on my communications people. You see these statements . . . I don’t know why the statement went in the direction it did.”

First lady Pam Northam told investigators that she didn’t realize the staff was sending out a public apology or she would have “physically stood there and stopped it.”

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

At the nationally televised 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 — an account that has been contradicted by one former classmate who told investigators that he remembers looking at the yearbook page with Northam outside the school library in the weeks before graduation.

During that news conference, 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, intensified calls for his resignation.

He refused, saying he would solve the mystery of the photo. His political action committee hired a law firm to conduct its own investigation. Northam’s investigators tried to analyze the photo with facial-recognition software, but the photograph was not of sufficient quality.

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.

Investigators interviewed a woman Northam dated during college and the first two years of medical school, who told them she had never attended a party with him in which he wore blackface or KKK robes. Northam’s former undergraduate roommate at Virginia Military Institute offered a novel dissection of who was in the photograph. The man, now a dentist, said the individual in blackface could not be Northam based on the shape and appearance of the person’s teeth.

The report released Wednesday said that photographs of individuals in blackface were not isolated to the 1984 EVMS yearbook. A review of yearbooks spanning from 1976 through 2013 found at least 10 photographs that included individuals in blackface. The last incident happened in 2004.

Homan, the EVMS president, on Wednesday called the photo “a failure of administrative oversight. It should never have happened.”

The medical school learned about the photo years ago, when it was unearthed by an alumni relations director who was pulling yearbooks for an event. Homan said it came to his attention in spring 2017, amid Northam’s bid for governor.

“We did not want that photo to enter the press,” Homan said, adding that the school was “apolitical” and did not want to take sides in Northam’s heated campaign against Republican Ed Gillespie.

He also said he didn’t feel a duty to inform Northam, since it was on his personal page. “I would make the same decision now,” Homan said.

Homan said he called his predecessor, Harry Lester, who told him that he knew about the photo years earlier and never made it public for the same reasons.

Lester, who records show donated $19,500 to Northam’s gubernatorial campaign, did not immediately respond to a request for comment.

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

Working with Republicans, he had 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 on a radio show in a way that Republicans, including President Trump, called an endorsement of infanticide. Northam, a pediatric neurologist, called the infanticide charge “disgusting.”

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

As the governor sought to hang onto his office, new scandals rocked the Capitol, shifting the spotlight to the two men in line to succeed Northam. Attorney General Mark R. Herring (D), who had 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 on to 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 Gulf War.

After serving as Gov. Terry 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.