PARK CITY, Utah —  Saturday night in Park City saw the world premiere of “The Stringer,” which calls into question the origins of one of the most famous photographs ever taken. Directed by Bao Nguyen, the documentary claims that the photograph taken on June 8, 1972, of a naked 9-year-old girl named Phan Thi Kim Phuc as she fled a napalm attack on the village of Trảng Bàng in South Vietnam was not taken by Nick Ut, the Associated Press photographer to whom it is credited.

Officially titled “The Terror of War” but more commonly known as “Napalm Girl,” the photo won Ut a Pulitzer Prize and was the cornerstone of his career until he retired from the Associated Press in 2017. Ut was only 21 years old when the incident at Trảng Bàng occurred.

Instead, “The Stringer” alleges, the photo was actually taken by Nguyen Thanh Nghe, a driver for an NBC news crew present that day whose photos came into the AP‘s possession as a freelancer, also known as a stringer.

The origin of the claim in the film comes from Carl Robinson, an AP photo editor in Saigon on that day. In the film, Robinson claims that Horst Faas, the chief of photos in Saigon, instructed him to “make it Nick Ut” and for Robinson to incorrectly credit what would within a few hours become the photo known around the world.

The film’s team set out on a two-year investigation of their own, eventually leading them to Nguyen Thanh Nghe, who says in the film that he took the photo. Of a moment when he later met Ut but did not bring up the origins of the shot, the Vietnamese photographer says in the film, “I worked hard for it, but that guy got to have it all.”

On Saturday afternoon, ahead of the film’s premiere screening, director Nguyen and executive producer Gary Knight, a veteran photojournalist who appears onscreen in the film, sat for an interview in Park City about the documentary and its startling allegations.

“This story challenges my profession and established truth in my profession,” said Knight. “And so we owe it to our profession to be very diligent and to get this right. And the pushback from the profession we expected would be tough. Rightfully so.

“Bao is a very prominent Vietnamese American filmmaker who comes from the same community as the stringer and as Nick,” said Knight. “So we were all heavily invested in making sure that we were diligent, thoughtful and treated everybody with respect and tried to get this right. So we’re all stakeholders in the story.”

Ahead of the release of the film, the AP conducted its own investigation into the origins of the photo over six months, interviewing seven people who were witnesses to the events on the road at Trảng Bàng that day and in the AP’s Saigon bureau where the picture was developed and printed. None of those witnesses were interviewed on camera for the film. Without having seen the film, the AP report concludes, “In the absence of new, convincing evidence to the contrary, the AP has no reason to believe anyone other than Ut took the photo.”

The internal report also said that AP “would look fully into any questions around the photo, and, if the credit was indeed incorrect, would take appropriate remedial actions.”

Knight is also co-founder and CEO of the VII Foundation, a nonprofit journalism advocacy and education organization. Nguyen’s previous work includes the documentaries “The Greatest Night in Pop,” on the recording of the song “We Are the World,” and “Be Water,” a portrait of Bruce Lee, both of which also premiered at Sundance.

“The life that many refugees and immigrants have left behind when they’re coming to a place that’s strange and foreign, there’s this expectation that they have the same agency to tell their narratives and tell their stories, but it’s not the same,” said Nguyen. “This film is in many ways a reckoning of that assumption that, ‘OK, if Nghe had this truth for so long, why didn’t he say something?’

“But can you imagine coming to a new culture, a new place, just trying to take care of your family and going up to a system that he doesn’t understand and that he believes that he does not belong to?” said Nguyen. “Documentary films specifically have a responsibility to try to acknowledge all these misrepresentations and systems that have existed.”

According to the AP report, in a 2005 oral history for AP’s corporate archives Robinson made no mention of misidentifying the photo and gave no indication of uncertainty whether Ut took the photo. There is also no reference to Robinson’s allegations in his own book about his time in Vietnam, though in the film he expresses regret over this omission.

“This story doesn’t hinge on Carl,” said Knight. “We interviewed 55 people, 45 on camera, and did the forensic research, which has been tested. So we don’t rely on Carl’s story. That was just the beginning of the journey. And whether AP choose to talk about Carl as a disgruntled employee or not, it doesn’t make him a bad witness per se. A lot of whistleblowers are in the same situation. So we wouldn’t have made a film based solely on one man’s accusations. That’s not journalism.”

In a telephone interview on Saturday, James Hornstein, an attorney representing Ut (who has also not yet seen the film), said in reference to Robinson, “I think it is outrageous that the VII Foundation has provided a platform to a man who clearly has a vendetta that’s been simmering for more than 50 years.”

Kim Phuc, who does not remember the events of that day, said in a statement provided to The Times by Hornstein, “I have refused to participate in this outrageous and false attack on Nick Ut raised by Mr. Robinson over the past years. … I would never participate in the Gary Knight film because I know it is false.”

Among the most compelling arguments put forth in the film is a visual timeline created using all available photographic and film evidence to place Ut out of position when the “Terror of War” image would have been created, with Nghe in the correct spot.

“I stand by the research and the forensics,” said Knight. “I think Nghe is the only person who was in the right place to have taken that picture.”

The AP’s own report says it also created a visual timeline using available materials but the results “offer little evidence about the provenance of the photo.” Also, the images, “along with Ut’s strong body of work from the day, show a scenario in which Ut, running around the scene energetically, had ample opportunity to capture the image.”

While no one involved with the documentary is disputing the powerful truth of what is in the image itself, the assertion that the photo’s origins and authorship are up for debate has a potentially life-changing dimension.

“It’s quite upsetting to him personally and emotionally, as one could imagine,” Hornstein said of the impact on Ut. “This is perhaps the most important piece of work that he’s done in his life in terms of the acclaim that this photo has brought. And for him to be accused of lying about it, which is what this film does, is devastating.”

For Nguyen, the film comes down to finally telling a story that has up to now been unheard.

“For me personally, the film is about finding the stringer,” said Nguyen. “It’s uplifting Nghe, this 53-year-old burden that he had on his shoulders for most of his life. And as you see in the film too, the stories of many Vietnamese journalists and Vietnamese American journalists have been neglected for decades.

“Nick’s narrative had been well established through past interviews, and with very little editorial. It’s just presented as he’s always stated it,” said Nguyen. “And so it’s more about focusing on this other part of the story that’s been in the shadows for so long.”