Sources said Ivey played for two nights over the August bank holiday for about seven hours in all.
Suspicions over the win intensified when it was discovered that his companion's membership of another Mayfair casino had previously been suspended.
Crockfords, the oldest private gaming club in the world, is owned by Genting, the Malaysian gaming corporation.
Genting investigators flew to London from Kuala Lumpur to speak to everyone who was working on the two nights in question and to examine hours of film from surveillance cameras.
