The 69-year-old man who allegedly stabbed his son-in-law was a veteran in the shipping industry, and the victim and the accused were once directors of the same firm.

Business records show that since 1978, Tan Nam Seng has been director or owner of various firms with names beginning with "TNS", his initials. He is still listed as the director and a shareholder of TNS Group Holdings and TNS Seacon.

He is also a former director of TNS Ocean Lines, where the victim, Mr Spencer Tuppani Shamlal Tuppani, 38, was chief executive officer and a director. The two lived in the same terraced house in Sennett Lane, together with Mr Tuppani's wife, three children, mother and a maid, according to neighbours.

A neighbour, who wanted to be known only as Mrs Yong, described Mr Tuppani's father-in-law as "a bit quiet and reserved".

On Monday, Tan was found standing over a bleeding Mr Tuppani in front of A Poke Theory eatery in Boon Tat Street. Tan held a knife and showed little emotion, said eyewitnesses.

A Poke Theory employee Vinnie Ang said that as he tried to help the victim, the older man pushed him away, saying: "That is my son-in- law. Don't help him. Let him die."

He said the older man was also overheard saying in a phone call: "I have already stabbed him. Don't cry. I am old already and I am not afraid to go to jail. What is done is done."

Customer service executive Zoe Tan, 26, said she saw police officers taking the suspect away.

"He was very neatly dressed. He was very calm and looked like he was prepared for the police to come and arrest him," Ms Tan added.