Update, June 23, 2016: A Marine Corps investigation has confirmed that Pvt. 1st Class Harold Schultz was the marine misidentified as Navy Corpsman John Bradley in the iconic Iwo Jima photograph. Read more details about the findings here.

When AP photographer Joe Rosenthal took photos of American Marines erecting a flag on the top of Mount Suribachi in Iwo Jima on February 23, 1945, he didn’t know it would become the iconic image of the war. In fact, he didn’t even look at it before it was sent to Guam where it was developed and edited, the Washington Post reports. But that image, with its strong diagonal line and six servicemen struggling with the flag, struck a chord in the collective American consciousness, and earned Rosenthal the Pulitzer Prize.

At the time of the shot, Rosenthal did not think to get the names of men involved, so the Marine Corps later identified them as John Bradley, Rene Gagnon, Ira Hayes, Harlon Block, Michael Strank and Franklin Sousley. The soldiers went down in history, but Scott McFetridge at the AP reports that the Marines may have misidentified one of the marines, and now the service branch has begun investigating the possibility that Bradley was not one of the flag raisers.

In 2014, amateur history buffs Eric Krelle, of Omaha, Nebraska, and Stephen Foley, of Wexford, Ireland, began raising concerns about discrepancies in the photo, as the Omaha World-Herald first reported. In particular, they pointed out that while Bradley was reported to be a Navy corpsman, or a medic, the man is the photo is outfitted very differently. A medic would only carry a pistol, they argue, while the figure in the photo is wearing a cartridge belt and has wire cutters hanging from his pocket. Other photos from that same day show that Bradley wore his pants cuffed, while the figure in the photo has uncuffed pants and is also wearing a hat under his helmet, which Bradley did not do.

According to statement given to the AP, the Marine Corps says it is "examining information provided by a private organization related [to] Joe Rosenthal’s Associated Press photograph of the second flag raising on Iwo Jima.”

UPDATE, May 4, 2016: In a statement later posted to Twitter, the Marine Corps identified the Smithsonian Channel as that private organization. According to a different statement provided by the Channel, the production team presented their findings to the Marines in January. It reads, "While the evidence remains confidential, Smithsonian Channel is committed to continued engagement with Marine Corps leadership, and will broadcast all the findings about this fascinating story later this year."

During the bloody, 36-day battle for Iwo Jima, an estimated 6,500 Americans and 21,000 Japanese were killed, including Block, Strank and Sousley. The surviving flag raisers, Bradley, Gagnon and Hayes, were shipped to the U.S. to sell war bonds. Bradley's son, James, wrote the best-selling book Flags of Our Fathers, which Clint Eastwood made into a movie in 2006. For his part, Bradley, who interviewed Rosenthal and survivors of the flag raising for his book, is not convinced that the Marines misidentified the flag raisers. “I’m interested in facts and truths, so that's fine, but I don't know what's happening,” he tells McFetridge.

The historians have not made any statements about the investigation, citing a confidentiality agreement.