In the afternoon of that day, during the inspection, the Hengqin Border Inspection Police found that a Korean man's passport had a large black mark inside, so they quickly handed it over for examination.
During the examination, the passenger confessed that he did alter the inspection stamps inside his passport, as an attempt to conceal his journey from his wife.
He assumed that it would be not problematic as it was on the inside page of the passport, and believed the border police wouldn't even notice it. He ended up marking the two Philippine inspection stamps with a black marker as a result of his thoughts. To his surprise, he was seized when arriving at the port.