Mr Ken Ong and his father Ong Teck Eng had become strangers.
Yet the older Mr Ong, 70, was at his son's cremation yesterday.
Mr Ken Ong died last Friday morning from stab wounds to his abdomen. He allegedly murdered his wife, Madam Karen Koh, before turning the same knife on himself.
Mr Ong Teck Eng spoke to reporters yesterday, before the cremation of his 37-year-old son at Mandai Crematorium.
"This is my duty as a father," he said.
The rites and cremation were paid for by undertaker Roland Tay, founder of Direct Funeral Services.
At a quiet Buddhist ceremony attended only by a monk, Mr Ong and Mr Tay, Mr Ong betrayed no emotion during the ritual and when he looked at his son for the last time when the casket was opened.
After the funeral, he said: "He looked like he was at peace... This is how life is. There is no point crying, it won't bring the person back."
Mr Ken Ong's mother left the family when he was just two, and Mr Ong Teck Eng raised his son by working as a butcher.
"He was chubby all his life, we called him 'pui kia' (Hokkien for fat child)," said Mr Ong in a mix of Mandarin and Hokkien, adding that his son had always liked playing computer games.
He put his son through school, up till Mr Ken Ong dropped out of polytechnic.
He would not say how the two of them had grown apart.
"We lived in the same home, but some days we would not talk at all."
Years ago, his son had moved out. The last time they met was a few years back, when the younger Mr Ong came by his home to pass him $200 to $300, he said. The elder Mr Ong lives alone in a one-room rental flat in Toa Payoh.
The younger man was carrying a baby boy and had been driven there by a woman who did not step out of the car.
"I didn't know if he was married, he didn't say."
This was something the father found out only on Saturday afternoon, when reporters knocked on his door.
On Friday, his son allegedly attacked both Madam Koh, 39, and the couple's maid, Ms Jasmen Jamelarin Corpuz, 37, with a chopper at their Yuan Ching Road home.
The couple died in hospital, and Madam Koh was cremated on Saturday evening.
The maid was seriously injured but survived, and was still warded at the National University Hospital yesterday.
Before he died, Mr Ken Ong had e-mailed a 2,047-word "Final Note" to the media and others, describing his failed marriage.
One of his grievances was that he had been forced to stop his studies at the Building and Construction Authority (BCA) Academy. A BCA spokesman said Mr Ken Ong was a diligent student who had a positive attitude.
Yesterday, the older Mr Ong said: "My son was wrong to do something like this, we have wronged (Madam Koh's family), I know this in my heart."
When asked if he had any last words for his son, he said: "Take care of yourself."