SINGAPORE - A businessman accused of causing his father's death in West Coast Rise on Feb 10 last year looked "bewildered and lost" when his aunt saw him right after the incident.

The father and son had a "very good relationship", the court heard on Thursday (July 7).

Mark Tan Peng Liat, 30, allegedly caused his father Tan Kok Keng's death by applying a headlock and a chokehold over his neck region - acts done with the knowledge that they were likely to cause injuries that could lead to death.

The incident, which took place at a semi-detached house in West Coast Rise at 5.26pm, arose over a quarrel, the younger Tan's lawyer said previously.

Originally accused of murder, Tan's charge was amended to culpable homicide not amounting to murder in October last year.

His trial started on Thursday (July 7) with witnesses including Tan's paternal aunt, Madam Tan Hoon Choo, 72, taking the stand. She lives a short distance away in West Coast Rise as well.

The dead man's maid of around 13 years rushed over to her house on the day of the incident and collapsed at her doorstep, "hysterical".

"She said: 'Aunty, please help, please help. Mark and sir are fighting,'" said Madam Tan. "I've never seen her in this state. (Their household has) never had any fights."

When she arrived at her 67-year-old brother's house minutes later, her nephew was standing outside it, she said, his face "pale". He also looked "very bewildered and lost". Usually, she added, "there would be a big smile on his face" and "a very warm address" from the younger Tan.

She gave him a hug but they did not speak.

Madam Tan found her brother lying on the floor in the master bedroom and rushed to him, in a state of shock.

He was unresponsive. Crying, she asked her nephew to call an ambulance.

The older Mr Tan was taken to the National University Hospital just after 5.30pm. He had a cardiac arrest and was pronounced dead about an hour later. His son was arrested on the same day.

Dressed in a white long-sleeved shirt, Tan closed his eyes as his aunt recounted his relationship with his late father.

"My brother was very fond of his son," said Madam Tan when asked of the pair's relationship. "He was very proud of him."

The older Mr Tan, a taekwondo black belt who exercises regularly, rarely complained about his son when he was grown up.

When his son was younger, she said, he would discipline the boy about his studies.

The younger Tan was also charged with having 15 airsoft guns without a licence at the house. He intends to plead guilty to that charge.

District Judge Eddy Tham had earlier set Tan's bail at $50,000.