Liu Changjian, a Chinese national, is accused of trying to trick Madam Liu Ya Bo into paying a ransom of 30,000 yuan (US$4,170) for his release.
He had sent threatening messages to his aunt last week while pretending to be his captor, the police said in a news release.
Liu was at the Marina Bay Sands Casino on Mar 7 and Mar 8 when he put his plan in motion, according to court documents.