"I didn't think he was a genius, I knew he had to be a cheat.
"I kept on looking at him. He was always sitting down, he never got up. It was very strange; we are taking about hours and hours of playing. But most suspicious of all, he always had his arms folded with his thumb under his armpit. He never took it out."
Coqueraut said he was also "batting his eyelids in the most unnatural way".
"Then I understood it," he said. "He was deciphering signals in Morse code."
The referee attempted to expose Ricciardi by asking him to empty his pockets, but nothing was found. When he was asked to open his shirt, he refused.
Tournament organisers then asked the 37-year old to pass through a metal detector and a pendant was found hanging around his neck underneath a shirt that contained a tiny video camera as well as a mass of wires attached to his body and a 4cm box under his armpit.
Ricciardi claimed they were good luck charms.It is thought the camera was used to transmit the chess game in real time to an accomplice or computer, which then suggested moves for Ricciardi through a series of signals received in the box under his arm.
Coqueraut said Ricciardi constantly drank from a glass of water and wiped his face with a handkerchief to conceal the pendant around his neck.
An investigation has been opened by the World Chess Federation and the Italian Chess Federation, which is currently evaluating whether to press charges for sports fraud.
In April, Gaioz Nigalidze, a Georgian Grandmaster was expelled from the Dubai Open after being caught pretending to be desperate for the toilet so he could use a mobile phone to cheat. The device had one of his games being analysed by a chess app.