Just before midnight on May 4, 2023, police were called to an Amazon warehouse in Chattanooga, Tennessee, to investigate a reported theft. 

They were met by a loss prevention employee, who directed them to a warehouse worker named Noah Page, the suspected culprit, according to a police report of the incident that was obtained by CNBC.

When confronted by police, according to the report, Page admitted that he’d marked a customer’s order in Amazon’s internal system as returned even though the products were never actually sent back to the company. Page received $3,500 for his part in the scheme, the report said.

Page didn’t know the customer but had chosen to call him “Ralph,” the report said. Ralph, it turned out, was part of a group named Rekk, an expansive refund fraud organization that targeted major retailers and recruited company employees by promising them a cut of the profits, Amazon alleged in a lawsuit.

Refund fraud, which involves tricking retailers into refunding a customer for a purchase without an item being physically returned, has become so pervasive that groups now market their services on Reddit, TikTok and Telegram. Type in “refund method” — or “r3fund,” to skirt content moderators — on TikTok and videos will pop up of users showing off piles of cash, sneakers and iPhones. One video has the caption, “me after realizing you can get a refund on any Rick Owens if the ‘package never came,'” referring to the minimalist fashion brand. The clip shows a hand endlessly tossing shoes to the ground.

Fraud groups are taking advantage of retailers’ lenient return policies, experts told CNBC, which often include unlimited free returns and sometimes even a preference that customers keep the items. It’s ballooned into a massive problem for retailers, costing them more than $101 billion last year, according to a survey by the National Retail Federation and Appriss Retail. The figure includes multiple forms of fraud, such as sending back clothing after it’s been worn, known as “wardrobing,” and returning shoplifted merchandise, the survey said.

In December, Amazon filed a lawsuit against Page and 47 other people across the globe with alleged ties to Rekk, accusing them of conspiring to steal millions of dollars worth of products in a refund fraud operation. Amazon described these services as “illegitimate ‘businesses'” that look to “exploit the refund process for their own financial gain to the detriment of honest consumers and retailers who must bear the brunt of increased costs, decreased inventory, and service disruption that impacts genuine customers.”

Amazon also suffered more than $700,000 in losses at the hands of another alleged fraud ring in which 10 people were indicted last year, according to documents from a suit filed in 2023.

An Amazon spokesperson said the company is addressing the issue “head on” through specialized teams and machine learning tools that detect and prevent refund fraud. Amazon says its work with law enforcement has led to arrests, the dismantling of organized retail crime groups and civil lawsuits.

“We continue to make progress in identifying and stopping fraud before it happens, as well as dismantling the groups that attempt to damage the integrity of our store and the stores of retailers across the retail industry,” the spokesperson said in a statement. 

Here’s how it works: A shopper buys a product online and sends the order information to a group such as Rekk, which then poses as the customer in requesting a refund. Amazon refunds the money to the customer, who then pays the fraud group usually between 15% and 30% of the refund amount, often via PayPal or with bitcoin. That means the customer ends up buying the product for what amounts to a huge discount.

The fraud group then pays the conspiring employee at the retailer, typically a certain amount for a batch of packages the employee scans as returned.

Retailers and law enforcement agencies are catching onto the trend. In September, a 25-year-old man in Michigan, Sajed Al-Maarej, was arrested and charged with conspiracy, wire fraud and mail fraud after he allegedly ran a return fraud service called Simple Refunds that targeted more than 50 retailers. The following month, 10 men were indicted in Oklahoma, charged with conspiracy to commit wire fraud for allegedly operating a refund fraud service named Artemis Refund Group. And a 24-year-old U.K. man was convicted of fraud in December after running the KeptSecrets refund service, which targeted retailers including Amazon, Walmart and Wayfair, according to court documents. 

Following the Rekk scheme, Page was arrested when police showed up at the Chattanooga warehouse in May, and he was charged with theft of property worth more than $60,000. He pleaded guilty and was sentenced in November to three years of probation, as well as ordered to pay Amazon $5,000.

Page didn’t respond to requests for comment.

Amazon said it has tried to address the bribery problem. In its lawsuit against Rekk, the company said it has an internal customer protection and enforcement team made up of attorneys, former prosecutors, and analysts investigating organized crime schemes such as refund fraud. The company has also reportedly fired employees who were allegedly bribed to leak confidential data on third-party sellers.

Cyril Noel-Tagoe, a cybersecurity expert who has studied refund fraud extensively, said the economic incentive for low-wage workers to get involved with these schemes creates a perpetual challenge for retailers.

“If you’re offering an employee much more than they’re getting paid, then it’s quite hard to combat that,” Noel-Tagoe, who works as a principal security researcher at bot detection software company Netacea, told CNBC.

In the “Illegal Life Pro Tips” forum on Reddit, which is no longer active but counts 1.1 million members, refund scammers shared their tips and tricks. In recent days, Reddit banned an offshoot of that subreddit, called “illegallifeprotips2,” saying it violates the site’s rules “against transactions involving prohibited goods or services.” Users quickly resurfaced on a new subreddit, “ELegalLifeProTips.” After CNBC flagged “ELegalLifeProTips,” Reddit took down the subreddit for violating its ban evasion policy.

In the past, such illicit behavior ran rampant on the dark web and required VPNs and a special browser, said Brittany Allen, a trust and safety architect at fraud detection software company Sift. These days the perpetrators regularly discuss their activities openly on forums and in messaging apps, which Allen described as the “democratization of fraud.” 

“You don’t need to be that specialist that can figure out how to find these deep web groups,” Allen said. “All you need is to have a phone that can go to Reddit, or a TikTok account you’re already on, and you’ll potentially be exposed to fraud that doesn’t take as much uplift to participate in.”

Remi Vaughn, a spokesperson for Telegram, told CNBC in an email that the company moderates “harmful content” on its platform, including posts that promote fraud. “Moderators use a combination of proactive moderation on public parts of the platform and accept user reports in order to remove content which breaches Telegram’s terms,” Vaughn added.

A Reddit spokesperson said it uses a combination of automated tooling and human moderators to enforce its content policies, which prohibit users from soliciting or facilitating any transaction that involves fraudulent services.

After CNBC provided TikTok with examples of videos about refund fraud, the company said it removed them for violating its community guidelines. It said it also blocked hashtags that were used to promote refund fraud.

The use of mainstream apps in these schemes has made it easier for investigators to do their work. Noel-Tagoe referenced a case in which a retailer was able to track down an individual whose email address was in an Instagram post.

Allen said she’s been able to identify fraudsters through “vouches,” or screenshots of successful fraudulent returns. Some of the images show order numbers, store pickup locations or cart items, according to Allen, all useful intel for retailers investigating return fraud.

David Johnston, vice president of asset protection and retail operations at the National Retail Federation, said an increasing number of companies are “tightening up their return policies” in response to customer abuse and fraudulent activity.

Delivery workers, for example, are encouraged to photograph a package once it reaches its destination, and retailers are looking more closely for suspicious behavior in analyzing returns.

“There are some retailers that monitor the number of returns you make in-store, and if you return too much too frequently, they might put you on pause,” Johnston said. “We’re starting to see more of that now on the e-commerce side.”

WATCH: The ‘shopping journey will drastically look different’