According to Chinese tabloids, it seems that the Kovan killer was acquainted with the victims. There were no signs of break in, all the locks in the house were intact while it was rumored that the killer was known to the victims.
Although the police have classified the case as murder, it is still unclear if the killer was a robber or was looking to settle a feud with the Tans. The father, Tan Boon Sin, 67, was found dead in his home at 14J Hillside Drive while his son, Tan Chee Heong, 42, was dragged for more than 1 km along Upper Serangoon Rd outside Kovan MRT.
According to eye-witnesses, there was fighting, screaming and banging of furniture inside the house before the tragedy happen. A neighbor said when she cycled past the house around 3pm, she heard people quarreling but she thought it was just a domestic squabble.
Neighbors also shared that about 7 or 8 months ago, the family had some disputes and police were called in. The most recent incident was about 3 to 4 months ago. It is unknown if the disputes were linked to the murder.