RICHMOND, Va. (AP) — Another investigative effort to uncover the origins of a racist photo on Ralph Northam’s medical school yearbook page has ended inconclusively. That’s according to the author of a forthcoming book about the 2019 controversy who spoke to The Associated Press about her work.

Margaret Edds says she gave her best effort to determine who was in the photograph. She wasn’t able to arrive at a definitive answer. But her book offers new insight into the turmoil the photo caused.

The book’s publisher provided a copy to AP ahead of its publication in November.

Northam participated in over a dozen interviews for the book, which is set to be available this fall.