A South Korean man and woman were sentenced to stay in U.S. prison for no less than a year on Monday. They have been proven guilty of a card-game gambling scam that has cost a casino in Connecticut thousands of dollars last year.

The prosecutors said that Young Su Gy, 60, and Wookyung Kim, 34, went to Foxwoods Resort Casino to play Macao-style midi-Baccarat. In this game, only the house dealers handle the cards.

U.S. Attorney David Fein said that Gy utilized a holdout device within his sleeves through which he switches cards in and out of the game using it to his advantage. This device allowed him to hide and hold cards several times last fall.

Meanwhile, Kim performed as Gy’s blocker. She successfully destructed casino staff from seeing what Gy was doing. Both South Koreans wagered huge amounts on the games and collected hundreds of thousands. Sometimes they can even take thousands of dollars in just one game.

Judge Alvin Thompson of the U.S. District Court in Hartford sentenced Gy to at least 18 months in prison and Kim to one year and a day because of cheating the Connecticut-based Foxwoods. Foxwoods is a casino complex owned and operated by Mashantucket Pequot Tribal Nation.

On top of that, the two were ordered to pay $870,505 and a three-year supervised release.

They were arrested in November and pleaded guilty in wire fraud and theft in February. The two admitted to have deliberately cheated causing losses to a gambling hall on an Indian land amounting to $400,000 to $1 million.