But in May, shortly after it was publicly disclosed that the Marines were investigating the photograph, James Bradley said that he no longer believed that his father, who is deceased, was in the image. He said that his father had participated in an earlier flag-raising and mistakenly believed that it had been the one captured by Mr. Rosenthal. Mr. Bradley declined to participate in the documentary, according to Mr. Morgan.

Mr. Bradley, who did not return an email seeking comment, said in May that he had become convinced of this in 2014, after reading an article in The Omaha World-Herald that told how amateur historians had discovered the incorrect identifications. But he said that it took him a year to examine the evidence in the article because he had been working on a book in Vietnam, and then had become ill.

Days after the photograph was taken in 1945, Mr. Schultz sustained wounds to his arm and stomach, and he was sent home. Several months later, Mr. Schultz, who was originally from Michigan, was discharged from the Marines.

The federal government helped him get a job in Los Angeles as a mail sorter for the Postal Service. He was single until age 60, when he married Ms. MacDowell’s mother, who lived next door in his apartment building and shared a porch. But he never moved in with her and rarely discussed his time in the military, according to Ms. MacDowell.

Why Mr. Schultz apparently never disclosed that he was in the famous picture remains a mystery.

Many Marines who had fought on Iwo Jima suffered from post-traumatic stress disorder, but little was known about the condition at the time.

To cope, many Marines simply never talked about their military experience.

One of the other men pictured in the flag-raising, Ira Hayes, had asked men in his unit not to identify him as being in the photograph, but they could not keep it secret.

“I think Hayes and Schultz believed that if they were identified as flag raisers, not a day would go by without them being reminded of combat and being on Iwo Jima,” Dr. Neimeyer said.