Police are looking for the driver of a silver Toyota Camry with car licence plate SGM 14J in connection with the two bodies found in Kovan on Wednesday evening.
Anyone with information on the driver or the case may call 1800-255-0000.
Earlier, a man in his 60s was found dead inside house 14 J, Hillside Drive.
The body of another man, in his 40s, was found about 1km away near the Kovan MRT station.
They are believed to be father and son.
An eyewitness said she saw a man being dragged by a car while she was driving along Upper Serangoon Road. About 20 cars were honking loudly at the driver but he or she did not stop, said the eyewitness
The two are suspected to have been murdered. A blood trail could be seen between the two locations.
Officers from the Criminal Investigation Department are still at the Hillside Drive residential area, which has cordoned off.
Officers and a police forensic team are also at the MRT station.
Two lanes of Upper Serangoon Road, measuring about 50m, have been cordoned off for investigations.