UFC officials warned Tae Hyun Bang and Leo Kuntz about fight fixing before they fought at UFC Fight Night 79, people with knowledge of the situation told MMAjunkie.

Both fighters denied any knowledge of impropriety when confronted by officials. But 17 months after the fight, Bang (18-10 MMA, 2-3 UFC) reportedly is the subject of a police investigation for allegedly accepting a bribe in connection with the bout.

According to multiple reports from South Korean media, one of which identifies Bang, the UFC lightweight allegedly admitted to police his role in fight fixing after receiving death threats from organized crime figures, who’d wagered $2 billion Korean won (approximately $1.7 million USD) that Kuntz would win.

Police say Bang accepted a bribe of $100 million won (approximately $87,000) while wagering $50 million (approximately $43,000) on his opponent. He and three of his associates have been told not to leave the country during the investigation, which reportedly is being conducted by the Seoul Metropolitan Police Agency’s International Criminal Investigation Bureau.

The investigation marks the first formal inquiry into fight fixing involving the UFC. A UFC official did not respond to a request for comment, including Bang’s official status with the promotion; he remains on the UFC.com website.

In the hours before the UFC Fight Pass-streamed bout between Bang and Kuntz, which took place Nov. 28, 2015 at Olympic Gymnastics Arena in Seoul, South Korea, Bang went from a slight favorite to a massive underdog in betting lines, raising eyebrows. After a close fight, he defeated Kuntz via split decision.

Kuntz (18-3-1), who now fights for Korea-based RoadFC, told MMAjunkie he was backstage at the event getting his hands wrapped when officials approached him about the potential issue of fight fixing.

“The UFC seemed like they knew something was definitely not right,” Kuntz said. “They told me it was the largest odd swing they’d seen in MMA and last minute. They told me, ‘Hey, if either one of you guys goes out there and doesn’t fight, you should prepare to be investigated.'”

Bang, according to a person close to the fighter at the time of the UFC’s warning, also denied knowledge of any of fight fixing, as did his camp.

“The UFC said they just wanted to make sure that everything was on the up and up, that he was fit to fight, and that he would be doing his best to win,” said the person, who requested anonymity because of the sensitive nature of the situation.

Yet it appears Bang wasn’t telling the whole story. One report states he changed his mind and decided to fight fairly after his talk with UFC officials.

Kuntz had no doubts his opponent was giving his all when they were in the cage. He said he was unaware of any impropriety surrounding the fight and was more focused on the upcoming competition.

“When I fought him, I had absolutely no reason to think he wasn’t fighting,” Kuntz said. “He flashed KO’d me. From what I could tell, it seemed like he was trying to win that fight.”

But South Korean media say Bang could be in deep trouble for a violation of the “National Sports Promotion Act” and “obstructing business,” stated one report.

Bang most recently fought in the octagon at UFC Fight Night 93, losing by unanimous decision.