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 honour when he claimed the Executive Mansion 17 months ago.
A Republican House 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. 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."
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."