At each gambling table, the croupiers would have a tiny sensor earpiece, the size of a grain of rice, placed in their ears.
This type of earpiece was so small, hidden in the ear, that it would never be discovered. After analyzing the situation in the monitoring room, they would then remotely direct the croupiers at each table on how to deal the cards.
Besides this method of cheating through surveillance, there was an even more devious high-tech method used in the casinos: tampering with the card shoes.
Card shoes are used to shuffle and hold the cards. Before technology was applied in casinos, experienced croupiers could see what card was being dealt based on the faint reflection on the rear silver crossbeam of the transparent card shoe.
Now, the card shoes were directly tampered with during manufacturing, fitting a hidden compartment at the bottom. The compartment hid a deck of cards.
