The scandal that prompted an investigation into hundreds of Marines who are accused of sharing naked photographs of their colleagues in a private Facebook group is much larger than has been reported, Business Insider has learned.

The practice of sharing such photos goes beyond the Marine Corps and one Facebook group. Hundreds of nude photos of female service members from every military branch have been posted to an image-sharing message board that dates back to at least May. A source informed Business Insider of the site's existence on Tuesday.

The site, called AnonIB, has a dedicated board for military personnel that features dozens of threaded conversations among men, many of whom ask for "wins" — naked photographs — of specific female service members, often identifying the women by name or where they are stationed.

The revelation comes on the heels of an explosive story published on Saturday by the journalist Thomas Brennan. He reported on a Facebook group called Marines United, which was home to approximately 30,000 members who were sharing nude photos of colleagues along with personal information and even encouragement of sexual assault.

The report led the Marine Corps to open an investigation, spurred widespread outrage in the media and in Congress, and prompted sharp condemnation from the Corps' top leaders. According to the Naval Criminal Investigative Service, investigators are considering felony charges that could carry a maximum penalty of seven years in prison.

An official familiar with the matter told Business Insider that the Marine commandant, Gen. Robert Neller, would brief members of the House Armed Services Committee next week on the scandal.

"We're examining some of our policies to see if we can make them punitive in nature," the official said, adding that the Corps was taking the issue very seriously.

A Facebook-group exodus leads to a message board's popularity

Gen. Robert Neller, commandant of the Marine Corps. He is expected to brief Congress next week on the scandal. US Marine Corps/Cpl. Shawn Valosin Brennan's story also led to an apparent exodus of members from the private Facebook group, though some appeared to have found the publicly viewable message board soon after — with the express intent of finding the cache of nude images that Marines in the Facebook group were sharing.

"Come on Marines share the wealth here before that site is nuked and all is lost," one anonymous user said in a post on Monday, two days after Brennan's story was published. Follow-up replies offered a link to a Dropbox folder named "Girls of MU" with thousands of photographs.

Dropbox did not respond to a request for comment.

Members on the board often posted photos — seemingly stolen from female service members' Instagram accounts — before asking others if they had nude pictures of a female service member.

For example, after posting the first name and photograph of a female soldier in uniform on January 21, one board member asked for "Army chick went to [redacted], ig is [redacted]." Another user, apparently frustrated that no pictures had yet been found, posted a few days later: "BUMP. Let's see them t------."

On another thread, a member posted a photograph on May 30 of a female service member with her breasts exposed and said, "She is in the navy down in san diego, anyone have any more wins?"

GUAM (Feb. 11, 2017) Aviation Boatswain’s Mate (Equipment) Seaman Stephen Mugo and Logistics Specialist 3rd Class Jeremy Boling perform evening colors aboard the aircraft carrier USS Carl Vinson. US Navy photo by Mass Communication Specialist 2nd Class Sean M. Castellano One user followed up on June 13, offering another nude photo of the woman.

"Keep them coming! She's got them floating around someone [sic] and I've wanted to see this for a while," another user wrote in response.

Some requested nude photographs by unit or location.

One user asked in September for photos of women in the Massachusetts National Guard, while another requested some from the Guard in Michigan. Other requests included nude pictures of any women stationed at Fort Hood in Texas, Fort Bragg in North Carolina, McConnell Air Force Base in Kansas, or Naval Medical Center in San Diego, along with many more US military installations around the world.

In statements to Business Insider, military branches denounced the message board and promised discipline for any service members who engaged in misconduct.

"This alleged behavior is inconsistent with our values," Lt. Col. Myles Caggins, a spokesman for the Department of Defense, told Business Insider.

Capt. Ryan Alvis, a spokeswoman for the Marine Corps, told Business Insider that the service expects the discovery of the Marines United page will motivate others to come forward to report other pages like it.

"Marines will attack this problem head-on and continue to get better," Alvis said.

Lt. Col. Jennifer Johnson, a spokeswoman for the Army, told Business Insider: "The Army is a values-based organization where everyone is expected to be treated with dignity and respect. As members of the Army team, individuals' interaction offline and online reflect on the Army and its values. Soldiers or civilian employees who participate in or condone misconduct, whether offline or online, may be subject to criminal, disciplinary, and/or administrative action."

Air Force spokesman Zachary Anderson told Business Insider: "We expect our Airmen to adhere to these values at all times and to treat their fellow service members with the highest degree of dignity and respect. Any conduct or participation in activities, whether online or offline, that does not adhere to these principles will not be tolerated. Airmen or civilian employees who engage in activities of misconduct that demean or disrespect fellow service members will be appropriately disciplined."

The Navy did not respond to a request for comment.

'Hope we can find more on this gem'

The image board hosts disturbing conversations that in many cases appear to be between active-duty personnel.

"Any wins of [redacted]?" read one request, which shared further details about a female Marine's whereabouts, indicating the user likely worked with her in the past.

Another thread, posted in November, that had dozens of follow-up comments from users acting as cyber-sleuths to track down the victim started with a single photograph of a female Marine, fully clothed, taken from her Instagram account.

"Any wins?" that user asked, telling others the Marine's first name and where she had been stationed.

One user hinted at her last name as others scoured her Instagram account, posting more photos they had found. One photo of the victim and her friend prompted one user to ask for nude photos of the friend as well: "Any of the dark haired girl in the green shirt and jeans next to her?"

American soldiers are seen at the U.S. army base in Qayyara, south of Mosul Thomson Reuters

The thread carried on for months.

"Amazing thread," one user wrote. "Hope we can find more on this gem."

In December, a nude photo was finally posted. "Dudeee more," one user wrote in response. Many others responded by "bumping" the thread to the top so that others on the board would see it and potentially post more photos. Indeed, more photos soon appeared from the victim's Instagram account, which was apparently made private or shut down numerous times.

On the board, users complained that her Instagram account kept disappearing, apparently because she was trying to thwart her harassers. But others quickly found her new accounts and told others, and the new Instagram account names were shared throughout February.

"Oh god please someone have that p----," one user wrote.

The site that hosts the message board seems to have little moderation and few rules, though it tells users "Don't be evil." Its rules instruct members to not post personal details such as addresses, telephone numbers, links to social networks, or last names.

Still, many users on the board do not appear to follow those rules.

In one popular thread, started on January 9, an anonymous user posted non-nude pictures of a female airman, telling others in the caption: "Anyone know her or have anything else on her? I've got a lot more if there is interest. Would love for her friends and family to see these."

The user, who suggested in the accompanying captions that he was a jilted ex-boyfriend, posted many more photos in the hours and days after.

"She knows how to end it all. If she does get in contact with me I won't post anymore. So get it while it's hot!" he wrote.

Later in the thread, the man even referred to the airman by name and told her to check her Instagram messages.

"Wow, she blocked me on Instagram!" he later wrote. "Stupid c--- must want me to post her s--- up. I gave her a choice, it didn't have to be this way. I'm not a bad guy, she had a choice. Oh well, no point in holding back now. I want you all to share this everywhere you can, once I start seeing her more places I'll post her video."

Aside from those on active duty, some users who identified themselves as cadets at some military service academies started threads to try to find nude photos of their female classmates.

In a thread dedicated to the US Military Academy at West Point, some users who appeared to be cadets shared photos and graduation years of their female classmates.

"What about the basketball locker room pics, I know someone has those," one user said, apparently referring to photos taken surreptitiously in a women's locker room. "I always wondered whether those made it out of the academy computer system," another user responded.

In 2012, an Army sergeant who helped train and mentor cadets was discovered to have secretly filmed more than a dozen women in the bathroom and shower areas at West Point. The soldier pleaded guilty in the case and was sentenced in 2014 to 33 months in prison.

Cpl. Chris Lawler, a crewmaster with Marine Aerial Refueler Transport Squadron (VMGR) 152, observes an F/A-18C Hornet with Marine Fighter Attack Squadron (VMFA) 122 approach the refueling hose during Exercise Pitch Black 2016 at Royal Australian Air Force Base Tindal, Australia, Aug. 9, 2016. US Marine Corps photo "Bumping all 3 service academies' threads to see who can post the best wins in the next 7 days. Winning school gets the [commander's cup]," one user wrote. "Go Army, Beat Everyone."

Lt. Col. Christopher Kasker, a spokesman for the US Military Academy, told Business Insider: "The content on this image board or other websites, attributed to both West Point graduates and our fellow service members, is both alarming and contrary to our values. When alerted to incidents such as this, we thoroughly investigate and take appropriate action."

'This has to be treated harshly'

The existence of a site dedicated solely to sharing nude photographs of female service members is another black mark for the Pentagon, which has been criticized in the past for failing to deal with rampant sexual harassment and abuse within the ranks.

A 2014 Rand Corporation study estimated that more than 20,000 service members had been sexually assaulted in the previous year. Nearly six times as many reported being sexually harassed. In some cases, the military has pushed out victims of sexual assault who reported it, instead of the perpetrators.

"I'm kind of surprised. I'm still naive, I think, on some level," said Kate Hendricks Thomas, a former Marine Corps officer who is now an assistant professor at Charleston Southern University. "I am really disappointed to hear that the reach is broader than 30,000 and a couple of now-defunct websites."

Thomas criticized past responses to the problem, in which some had indicated the issue was too difficult for the military to wrap its arms around.

"This renders us less mission-effective. It's got to be a priority," she said.

"These websites are not boys being boys," she added. "This is a symptom of rape culture."

The message board also presents a challenge for military leaders, who may face an uphill battle in trying to find — and potentially prosecute — active-duty service members who shared photos on the site. Unlike the Marines United Facebook group, where many users posted under their real names, the message board's user base is mostly anonymous, and the site itself is registered in the Bahamas, outside the jurisdiction of US law enforcement.

Brad Moss, a lawyer who specializes in national-security issues, told Business Insider that the military may have a hard time persuading the internet service provider to shut down the website. Instead, he said, the victims themselves may have more legal standing if they were to contact the ISP to remove the photos.

Still, Moss said he believes the military could squash the behavior if it adopted a "zero-tolerance" posture.

"I think that absolutely, 100%, should be the policy if they catch the main perpetrators who are sharing these photos around and essentially engaging in revenge porn," Moss said. "They should have a zero-tolerance policy and boot them from the military with a dishonorable discharge.

"If they do anything less, it's only going to incentivize this behavior in the future," he added. "This has to be treated harshly."

This article was updated on 3/10 at 6:40 a.m. PDT to add a statement from the US Military Academy.