FILE - National Park Service rangers walk toward the U.S. Marine Corps War Memorial in Arlington, Virginia, April 29, 2015.
FILE - National Park Service rangers walk toward the U.S. Marine Corps War Memorial in Arlington, Virginia, April 29, 2015.

The U.S. Marine Corps is investigating the possibility that one of the six marines in an iconic photo taken at The Battle of Iwo Jima during World War II has been misidentified.

The probe comes more than a year after two amateur historians raised doubts about one soldier.

"The Marine Corps is examining information provided by a private organization related [to] Joe Rosenthal's Associated Press photograph," the Marine Corps spokesman Major Chris Devine said in a statement.

Rosenthal shot the photo on February 23, 1945 on Mount Suribachi, amid an intense battle with the Japanese. The flag-raisers quickly moved on to other tasks and it was impossible to get their names, Rosenthal told retired AP executive Hal Buell, who wrote a book in 2006 about the famous image.

Because the photo was immediately celebrated, prompting the U.S. government to use it in future bond sales to help finance the war, President Franklin Roosevelt ordered the military to identify the soldiers.

After some confusion, they were eventually identified as John Bradley, Rene Gagnon, Ira Hayes, Harlon Block, Michael Strank and Franklin Sousley.

But after reviewing photos taken at Iwo Jima later that day, amateur historians Eric Krelle of Nebraska and Stephen Foley of Ireland last year noticed some possible discrepancies. They concluded the man identified as Bradley was actually Harold Henry Schultz, who died in 1995.

Bradley's son, James Bradley, wrote the best-selling book Flags of Our Fathers about the flag-raisers and was later made into a movie directed by Clint Eastwood. Bradley expressed shock that the Marine Corps is investigating the identities of the soldiers. "This is unbelievable," Bradley told AP. "I'm interested in the facts and truths, so that's fine, but I don't know what's happening," he added.

The Marine Corps did not give a timeline for the investigation.

Iwo Jima is part of the cluster of Japanese Volcano Islands south of Tokyo. It was the site of an intense 36-day battle that began on February 19, 1945, and involved about 70,000 U.S. Marines and 18,000 Japanese soldiers. More than 6,500 U.S. soldiers died in the battle.

The capture of Iwo Jima was strategically important to the U.S. because it prevented Japanese planes from taking off from there and intercepting American bombers.