In Macau, a man has reportedly been arrested for his involvement in a criminal scheme that allegedly saw him illegally trade some 100 counterfeit United States banknotes for genuine local currencies.

According to a report from local radio and television broadcaster Teledifusao De Macau, the enterprise was uncovered at an unnamed casino only after one of the victims asked for his new banknotes to be officially verified.

“The man says that he exchanged HK$54,000 for 80 [U.S. bank notes] (HK$62,074),” Choi Ian Fai, a spokesperson for Macau’s Judiciary Police, reportedly told Teledifusao De Macau. “After watching the surveillance video provided by the casino, we confirmed the swap. Therefore, we believe that the fake banknotes came from the other individual involved and whom we tracked. The surveillance video also shows the same individual wandering around other casinos in Macau.”

The perpetrator was subsequently arrested as he tried to cross the border into mainland China and reportedly immediately confessed to trading the counterfeit banknotes on behalf of other individuals. He purportedly additionally admitted to having more fake money waiting to be dealt while officials explained that they are currently trying to determine the source of the fraudulent currency, which has proved very difficult for Macau gamblers to distinguish from legitimate notes.

“The fake banknotes have vague features,” Choi reportedly told Teledifusao De Macau. “The words “USA100” are clearly visible on the real banknotes. Subject to ultraviolet light, the security line on the real banknotes shows neon reaction. This isn’t visible with the fraudulent notes. The watermark on the fake banknotes appears even without being subject to ultraviolet light [and] this proves that it was added afterwards.”

This is only the latest in a string of counterfeit currency schemes that have been uncovered by police over the past few years and Teledifusao De Macau reported that officials are urging gamblers and tourists to be suspicious of foreign exchange rates that may appear too good to be true.