In the beginning, there was just Rick Norsigian, a California man who announced in July that he believed that he had purchased “lost negatives” of Ansel Adams for $45 at a garage sale.

His art dealer put the value of the find at $200 million, and the story made news around the world.

Then an 87-year-old woman surfaced to say that she had three prints that looked a lot like Mr. Norsigian’s images — one was hanging in her bathroom — and that they had been shot, she said, not by Adams, but by Earl Brooks, her uncle, who was a little-known photographer....