The Sook Ching Operation on 21 February 1942

A startling decree was issued to the population that morning, that all Chinese males in Syonan-To between the ages of 18 and 50 years of age were to report to the registration centres for screening.
However, these people did not know what the Kempeitai, the japanese secret police, were doing. They were dragging people out of their homes at bayonet point =. The men who voluntarily went to the registration centres thought they were going to get jobs. Jalang Besar, Arab Street, Tanjong Pagar, the junction of Kallang and Geylang Road, the junction of river Valley and Clemenceau Avenue and Paya Lebar rubber estate were the main areas. The men were separated into groups: civil servants, students, hawkers and merchants. The centres had no toilets, food or shade. In Geylang, the people were made to stay in the open field under the tropical sun for the whole day. A minor reporting located at the corner of upper Cross Street and South Bridge Road. The ends of the streets were cordoned off to serve as a garrison.
The men were questioned about their jobs, asked to write their names and checked for tattoo marks. English-speaking Chinese men were considered dangerous, tattoo marks meant one was a secret society member. Those who could not write their names in Chinese were ridiculed and in danger of being shot.
The idea of the Sook Ching operation was actually to weed out anti-Japanese elements, but the order was carried out by subordinates who were discriminate. Masked informers picked out those were thought to be anti-Japanese. Those who "failed" the questioning were taken away in truckloads to the beaches in Changi and Punggol to be shot. Those who satisfied the interrogators were given a chop with the word "examined" in Japanese on their arms or hands. However, it was not guaranteed that they were safe from them on, as some were rearrested and shot.
The killings were kept a secret and many families actually thought their lost relatives had been taken to jail or sent away as labourers. Only after the war did the truth about the killings were known to the people off Singapore.