NEW YORK (AP) -- NBC News has assigned the head of its own investigative unit to look into statements made by anchor Brian Williams about his reporting in Iraq a dozen years ago.

Brian Williams (Brad Barket/Invision/AP, File)

A source at the network who requested anonymity because the person is not authorized to speak on personnel matters confirmed the investigation on Friday. Williams has apologized for falsely saying on the air that he was in a helicopter hit by a rocket-propelled grenade while in Iraq in 2003.

Richard Esposito, a former editor at the New York Daily News now at NBC, will head the investigation. The incident has ballooned into a full-blown crisis for NBC and Williams, whose "Nightly News" is the top-rated evening news program.

There was no word on whether Williams will be on the broadcast Friday.

Meanwhile, new questions about Williams' credibility arose when a New Orleans newspaper questioned his coverage during Hurricane Katrina.

Brian Williams (AP Photo/Starpix, Andrew Toth, File)

The New Orleans Advocate challenged this piece of reporting by Williams on Katrina:

“When you look out of your hotel window in the French Quarter and watch a man float by face down, when you see bodies that you last saw in Banda Aceh, Indonesia, and swore to yourself that you would never see in your country.”

The Advocate alleges that Williams, who covered the aftermath of the devastating hurricane from the city's French Quarter, could not have seen a body float by, as that section was not flooded.

A former city health director who was in the French Quarter after the storm says Williams' story is not possible. “We were never wet. It was never wet,” Dr. Brobson Lutz told the Advocate.

The Middletown native, who also slept at the Superdome during the storm, later said he had swallowed flood waters and suffered from dysentery. He also claimed to be curled up in the fetal position because of the illness which causes acute bloody diarrhea. Lutz did not recall any reported cases of dysentery after Katrina. “I saw a lot of people with cuts and bruises and such, but I don’t recall a single, solitary case of gastroenteritis during Katrina or in the whole month afterward,”

Williams' coverage of the hurricane earned him a Peabody Award and a Polk Award and the praise of former NBC News anchor Tom Browkaw, who said that Williams "took ownership, if you will, of the anchor chair” with his reporting.

Williams, the "Nightly News" anchor for just over a decade, has become an online punching bag overnight.

Tweets with the hashtag #BrianWilliamsMemories joked that he blew up the Death Star, saved someone from a polar bear and flew with Wonder Woman in her invisible helicopter. Photoshopped pictures showed him reporting from the moon and riding shotgun with O.J. Simpson in his Ford Bronco.

Brian Williams and daughter Allison Williams (Jamie McCarthy/Getty Images)

"How could you expect anyone who served in the military to ever see this guy onscreen again and not feel contempt?" wrote critic David Zurawik, of the Baltimore Sun. "How could you expect anyone to believe he or the broadcast he leads has any credibility?"

Williams apologized Wednesday for telling the story a week earlier during a "Nightly News" tribute to a veteran he had befriended during a 2003 reporting trip to Iraq. Before expressing his regrets on the air, Williams did so online and in an interview with the newspaper Stars & Stripes.

He speculated online that constant viewing of video showing him inspecting the damaged helicopter "and the fog of memory over 12 years, made me conflate the two, and I apologize."

His story had morphed through the years.

Shortly after the incident, Williams had described on NBC how he was traveling in a group of helicopters forced down in the Iraq desert. On the ground, he learned the Chinook in front of him "had almost been blown out of the sky"; he showed a photo of it with a gash from a rocket-propelled grenade.

The NBC crew and military officials accompanying them spent three days in the desert, kept aground by a sandstorm.

But in a 2008 blog post, Williams said his helicopter had come under fire from what appeared to be Iraqi farmers with RPGs. He said a helicopter in front of his had been hit.

Then, in a 2013 appearance on David Letterman's "Late Show," Williams said that two of the four helicopters he was traveling with had been hit by ground fire "including the one I was in."

"No kidding?" Letterman interjected.

Williams described making a quick, hard landing in the middle of the desert.

"I have to treat you now with renewed respect," Letterman said. "That's a tremendous story."

Williams' story was first questioned in posts to the "Nightly News" Facebook page. It's a touchy topic: Members of the military who are wounded or who come under enemy fire consider themselves members of a special kind of brotherhood and don't like people who try to intrude, said retired U.S. Army Col. Pete Mansoor, a professor of military history at Ohio State University.

"It smacks of stolen valor," Mansoor said - an offense that Williams specifically denied in his online apology.

Front cover of the New York Post (NY Post)

Chris Simeone, who says he piloted the aircraft that Williams flew in, told The Omaha World-Herald Thursday that "I think it's good that the truth is coming out. But I feel embarrassed for him."

Simeone said if Williams had "just reported the facts, it would have been a great story. He was there. He didn't have to embellish it."

Williams' immediate issue is whether people believe his apology, a particular problem in an industry in which credibility is crucial.

"It's pretty difficult to believe," Mansoor said. "I remember every time I was under fire in Iraq, especially if your vehicle is an aircraft that's been hit. That's something that gets seared into your memory for all time."

The New York Daily News labeled Williams' apology a fake.

"So what if it was 12 years ago," wrote TV editor Don Kaplan. "I remember getting hit in the head with a rock by a kid in the third grade."

Williams has an out-sized image at NBC News: The blue-collar Jersey guy and witty celebrity who slow jams the news with The Roots on Jimmy Fallon's "Tonight" show. He hasn't had credibility problems before, and he consistently leads in the ratings, making him an outlier at a network on which the "Today" show and "Meet the Press" have slipped from their lofty perches as ratings champions.

It's up to NBC News President Deborah Turness to decide whether Williams will be punished. She has the reputations of her most well-known personality and the news division as a whole to consider.

Jason Maloni, a crisis public relations expert at Levick Strategic Communications and a regular "Nightly News" viewer, said he isn't sure whether NBC should sanction Williams, but he doesn't want to see the anchor in a war zone anytime soon.

"I feel a little let down, and I imagine that's where a lot of the (online) anger is coming from," Maloni said.

Zurawik, of the Baltimore Sun, wrote that if credibility means anything to NBC News then Williams should be out of his job by the end of the week.

But Jane Hall, a communications professor at American University, said she believes Williams' apology should be accepted.

"It seems to me to be an honest mistake of conflating the two accounts," Hall said. "I don't think he has been known as anything other than a straight shooter."


Dan Alexander contributed to this report