• Originated from the Hokkien term am-pai.
• The term “暗牌” originated from a gambling term used in the early days. The players and dealer each has an unrevealed playing card on the table, with the number on this card being unknown to other players. This unrevealed card is called am-pai, which will only be revealed at the point when the winner of the game is to be decided. Later, the unrevealed am-pai is used as a metaphor for plainclothes detectives who do not easily disclose their identities topeople.
• Later, the Malay language standardised and included this term in the dictionary as ampai or mata mata gelap (to mean plainclothes detectives).
• In 1862, Singapore’s first team of plainclothes detectives was established, with the main aim of reducing violent crimes and curbing gang activities.
• Since 1903, Singapore’s plainclothes detectives come under a department officially known as the Specialised Crime Division under the Criminal Investigation Department (CID) of the Singapore Police Force. The Department is commonly known as “暗牌厝” (the Hokkien term “厝” means “house”).

暗探 (Mainland China, Taiwan)