Marriage records show that Mr Ken Ong Wei Poh and Madam Koh Siang Hua were married on Oct 18, 2008.
They have a son who is in kindergarten 2 this year.
Several people in Park View Mansions said Madam Koh and her son were friendly.
"They would always greet me whenever they see me," said cleaner Juriah Abu Bakar.
The 55-year-old, who has worked at the condominium for six years, said the child was polite and well-behaved.
"He will always say, 'Hello aunty, bye aunty', without fail every morning."
The family's domestic helper, Ms Jamelarin Jasmen Corpuz, would usually be seen walking the boy to his school nearby.
Ms Juriah's sister Fauziah, who is also a cleaner at the condo, said: "Sometimes he will be on a bicycle, sometimes the mother will drive the boy and the maid in her big black car. When (Madam Koh's) mother comes from Malaysia, she will chit-chat with us too."
Ms Juriah said the older woman gave her a $10 red packet one Hari Raya.
Security guard Lee Jee Kwang, who has been working there for three months, said he saw only Madam Koh driving the black car, a Jaguar XJL.
The cleaners and Mr Lee described Mr Ong as aloof - he hardly returned a greeting or made eye contact with them.
Neighbours said they often saw Ms Corpuz with the boy, riding a bicycle or inline skating around the property, but the family mostly kept to themselves.
Madam Sew Lai Hoong, 50, who has lived in the same block as the Ongs for 17 years, said she was more familiar with Madam Koh's parents who used to live in their apartment. "It was only after (she) got married that her parents moved back to Kuala Lumpur, so she lived there with her husband," she said.
Another long-time resident, Madam Monica Kuo, 55, said she used to be in the condo's committee with Madam Koh's father.
After moving back to Malaysia, where the family is originally from, Mr Koh and his wife would visit their daughter once in a while. "I last saw Mr Koh at the condo's annual general meeting last year," Madam Kuo said.
Records seen by The New Paper list Madam Koh's mother as the owner of the apartment.
A search of business records list Madam Koh as one of four directors of TYT Corporation, a company specialising in furniture. The other three directors are her mother, Madam Koh's younger brother and his wife.
The company's website shows that it also has offices in Kuala Lumpur and Penang.
When TNP visited TYT Corporation's Singapore office last evening, the only employee there declined to comment.
As for Mr Ong, his "Final Note" indicated that he stopped working to become a househusband so Madam Koh could continue working.
He later went back to study at the Building and Construction Authority's BCA Academy. It is not clear what he studied and when his studies started.
On his Facebook account, he listed himself as self-employed and a former student of Ngee Ann Polytechnic.
A search of business records show that Mr Ong used to be a director of Koto Services until he was struck off.
The address listed led to a one-room flat at Toa Payoh Lorong 5, believed to be the home of Mr Ong's father. No one came to the door when we visited.
A neighbour who wanted to be known as Mr Lee, 71, described the father-and-son relationship as strained.
He recalled an incident five years ago, when a group of people turned up at the older Mr Ong's door.
"They took one of my flower pots and smashed it at (Mr Ong's) door. I think they were loan sharks or debt collectors.
"I tried to explain that it wasn't me but his son was so unreasonable. He called the cops on me," he said.
Other neighbours described the older Mr Ong, who is believed to be 70, as reclusive.
"He is sickly and wheelchair-bound. This year alone, he has been in and out of Tan Tock Seng Hospital several times," said a neighbour whose flat is adjacent to Mr Ong's.
"He used to live with his son but the son moved out many years ago," the resident of more than 10 years added.
- Additional reporting by Foo Jie Ying and Godwin Ng