An underground gambling ring, possibly from Hong Kong or Japan, penetrated the Kangwon Land Casino in Jeongseon, Gangwon, planting hidden cameras at the gaming tables to help its gamblers count the dealt cards.

On Monday, a gambler at one of the casino’s baccarat tables saw a pinpoint of red light coming from a card box and the ruse was discovered after three years.

Jeongseon Precinct Police in Gangwon yesterday filed warrants to detain two employees of Kangwon Land Casino surnamed Hwang, 43, and Kim, 34, after finding wireless cameras in two separate card boxes.

Police assume the cameras recorded the cards that were dealt, even the ones placed face down on the gaming table, and a gang member viewing the images remotely could inform a member of the ring gambling at the table via text message.

After the gambler reported the red light on Monday, the casino immediately inspected the card box and found a wireless subminiature camera on its right inside edge. It found an additional camera in another card box Wednesday.

The casino reviewed CCTV footage and saw suspect Kim planting one of the cameras in the card box at 10 a.m. on Monday. Kim said he worked with Hwang, who allegedly brought into the casino card boxes that looked like the casino’s own but which had space for the cameras.

Hwang told police he had switched dozens of card boxes since 2009 and received 30 million won ($26,500) from the gambling ring, police said.

Kim said during questioning that he received 3 to 4 million won every time he installed a camera, receiving 40 million won in total, police said.

“The two suspects planted the camera-installed card boxes 23 times in Kangwon Land Casino,” a spokesman for the Jeongseon Police said. “Hwang testified that they were requested to plant the camera by a man in his mid-50s in February 2009, and then he ordered Kim, a game instruments mechanic, to plant the boxes.”

Police are having trouble tracking down the man because Hwang says he never saw or met him and everything was plotted over the telephone.

The police are reviewing CCTV footage to track down gamblers who played at the tables with cameras installed.

The police said gambling rings from Hong Kong or Japan are likely to be involved in the case.

The police are also wondering if the gambler who reported the light in the card box was a member of a rival gambling gang.

“We sincerely apologize to all customers,” said Choi Hung-jib, CEO of Kangwon Land Casino.

The casino fired eight executive-level officials in charge of running the casino Thursday and formed an emergency committee to deal with the case. Kangwon Land is considering shutting the casino temporarily.