The decomposing bodies of a 66-year-old woman and her 27-year-old son were found hanging in a bedroom in their flat in Block 727, Tampines Street 71.
The bodies of Madam Lee Gek Lan and Mr Toh Boon Siong were found in a locked bedroom by Madam Lee's son-in-law, who had returned home after a three-day hospital stay for an operation, according to Chinese newspaper Lianhe Wanbao.
The police were alerted at 4.21pm on Monday (Nov 27) and were seen at the block till past 9pm.
Paramedics who also arrived at the scene pronounced them dead.
The 27-year-old is believed to have been suffering from severe depression, but it is not clear if his condition was linked to their deaths.
The Straits Times understands that no foul play is suspected.
A neighbour who lives on the same floor, and who wanted to be known only as Madam Ho, said the family members often kept to themselves.
"Their door is always closed and we rarely see them," said Madam Ho, who has lived there for more than 20 years.
Another neighbour, a 59-year-old packer who identified herself as Madam Gina, said she often walks past the unit but had never seen Madam Lee or her son before.
"The family is very quiet. We don't know much about them," she said.