The body of one of the suspected Kovan murder victims, a man in his 70s, was removed by police at 2am on Thursday.
He had been found dead in a terrace home at 14J Hillside Drive on Wednesday afternoon.
The body of his son, who was in his 40s, was found nearly a kilometre away outside Kovan MRT station.
A blood trail could be seen along the road between the two locations.
An eyewitness had seen a car dragging the younger man behind it along Upper Serangoon Road. Police have appealed to the public for information on the driver of a silver Toyota Camry, licence plate number SGM 14J.
A neighbour of the family, who wanted to be known only as Mr Liang, said the car belonged to the older man. According to the 73-year-old retiree, the man had lived there for over 10 years with his wife, and was nice and helpful. The neighbour added that the couple's son did not live with them.
Three people were seen leaving the house after the police arrived - two women and a man, all of whom appeared to be in their 50s. It was unclear if the man's wife was among them.
Anyone with information may call 1800-255-0000.