Laundry was left hanging outside the three-room flat for a week.
It was a departure from what neighbours knew to be the daily routine of a private mother-son pair who lived in the fifth-floor flat in Block 85 Commonwealth Close.
On Tuesday afternoon, a 54-year-old man, said to be the son, was found dead in the flat.
He had been dead for about a week while his mother, who is in her 80s, grieved, according to Chinese-language publication Shin Min Daily News.
"A pair of leather shoes was left to dry in the sun for a whole week, yet he never took them in, which I found strange," fifth-floor resident Boey Sook Kam, 68, told The Straits Times yesterday.
Ms Boey, a part-time cleaner who lives with her son and husband, said the man, who was about 1.8m tall, would hang laundry out to dry every morning at around 8.30am.
Occasionally, she would see him leave the flat and come back with food or groceries.
His mother would come out of the flat to water her plants in the corridor.
The police had to call in a locksmith to enter the flat, as his mother did not respond to knocking on the door, according to the Shin Min report.
Wails were reportedly heard when the police managed to gain entry and found the man lying on the living room floor.
Ms Boey, who has lived in her flat for 27 years, said that both mother and son kept to themselves and avoided interacting with neighbours.
She added that in the last two days, she had occasionally caught a whiff of a foul stench when walking to the lift lobby, but thought nothing of it.
Most other residents on the same floor, as well as those above and below, told ST that they had smelt nothing amiss and found out about the death only when six police cars and an ambulance arrived at the block on Tuesday afternoon.
But a next-door neighbour, who declined to be identified, said that both she and her husband had detected a stench coming from the unit for about a week.
She said her husband, who was at work when ST visited the block, called the police on Monday, as he found the smell unbearable.
"At first, I thought there was a rat infestation or a sewage pipe leak, but the smell only got stronger," said the neighbour, who has lived in the block for a decade.
The Singapore Police Force said it was alerted to a case of unnatural death at Block 85 at about 12.40pm on Tuesday.
The man was pronounced dead at the scene by a paramedic.
Police do not suspect foul play, and investigations are ongoing.
A woman who identified herself as the dead man's sister was at the flat yesterday and said the family was still in shock.
Looking distraught, she requested privacy to grieve and declined further comment.
A grassroots leader in the Buona Vista ward of Tanjong Pagar GRC, under which Block 85 falls, said that community leaders in the ward have offered assistance to the family.
Mr Thomas Phun, chairman of the Buona Vista Citizens' Consultative Committee, also said: "In our regular community engagements (such as weekly house visits and Meet-the-People Sessions), we encourage our residents to look out for one another, as well as to inform us if they know of anyone who may need assistance."
- Additional reporting by Sabarna Manoharan