An investigation ordered by a Virginia medical school has failed to determine whether governor Ralph Northam is in a 1984 yearbook photo of a man in blackface next to someone in a Ku Klux Klan hood.

Investigators with a law firm hired by Eastern Virginia Medical School said they could not “conclusively determine” the identities of either person in the 35-year-old photo.

They also said they could not discern how the picture was placed on Mr Northam’s yearbook page, but found no evidence it was placed there by mistake or as a prank.

The findings are unlikely to have a major effect on state politics or Northam, who has been trying to regain his footing for several months.

Virginia politics was turned upside down in a matter of hours in early February after a conservative website posted a picture of Mr Northam’s medical school yearbook page.

Richard Homan, dean of EVMS School of Medicine
Richard Homan, dean of Eastern Virginia Medical School (AP Photo/Steve Helber)

The Democratic governor issued two apologies within hours, initially indicating that he was one of the people in the picture. By midnight it appeared his entire political base was gone, with the Virginia Legislative Black Caucus, other key Democratic groups and top allies calling on him to resign.

Mr Northam reversed course at a news conference the next day, saying he was convinced it was not him in the picture, while revealing that he did in fact wear blackface once decades ago, to look like Michael Jackson for a dance contest.

Defying calls to resign, he said he wanted to focus his remaining three years in office on addressing long-standing racial inequities.

While he was all but invisible in February and much of March, the governor is making routine public appearances again.

And he has won praise from black legislators and others for several recent policy moves. Those include ending the suspension of driver’s licences for motorists with unpaid court fines and costs, and a review into how public schools teach the nation’s racial history.

The heat for Mr Northam to resign significantly lessened after scandal enveloped his potential successors.

Two women publicly accused lieutenant governor Justin Fairfax of sexual assault, which he denies. And attorney general Mark Herring announced he had also worn blackface in college, just days after he too called on Mr Northam to resign.

Both Mr Fairfax and Mr Herring also resisted calls to resign. And other politicians around the South soon had their own explaining to do over yearbook images taken long ago.

But the incident will forever mark Mr Northam’s time in office.