EXCLUSIVE: Citigroup, DBS, and other banks in Singapore are intensifying their scrutiny of wealthy clients and potential customers following the country's largest money-laundering scandal. The scandal involved criminals laundering over $2.23 billion in online gambling proceeds through at least 16 financial institutions. In response, Singapore authorities are demanding more information from family offices and hedge funds and are increasing the closure of dormant firms. This heightened vigilance aims to prevent exposure to illicit financial flows, sources say.