SINGAPORE - A tale of a complicated relationship ending in tragedy emerged in the High Court on Tuesday (Oct 17) after a 28-year-old man pleaded guilty to a reduced charge of culpable homicide for fatally stabbing a 23-year-old colleague.

Neo Chun Zheng admitted to stabbing Ms Soh Yuan Lin once in the neck with a folding knife outside his flat at about 8pm on Nov 26, 2015.

The case has been adjourned for sentencing after the defence disputed the opinion of an Institute of Mental Health psychiatrist that Neo was not suffering from any mental disorder at the time.

The court heard that Neo and Ms Soh began working as customer relations executives at the Marina Bay Sands casino in April 2014. She used to be an air stewardess.

They began dating in September 2014, although Ms Soh stipulated that their relationship was "non-exclusive" and to be kept a secret.

But, time and again, Neo felt hurt and cheated when he found out that she was seeing other men while they were dating and even after she broke up with him a year later.

In March 2015, Neo quarrelled with Ms Soh after finding out she had been intimate with another colleague. He got hold of compromising photos of her and the colleague and showed them to other colleagues.

In September 2015, they quarrelled after he found out she was texting someone she had met and kissed at a club.

Ms Soh broke up with him later that month as she felt he was too possessive. She told him she needed a break from relationships and wanted to remain single.

But Neo found out that she was using dating app Tinder to meet various men and became angry with her for going back on her word about staying single after the break-up. He told a friend he contemplated disfiguring her with acid.

Throughout this time, Neo continued to guilt-trip Ms Soh into buying meals for him or going out with him, by telling her how much she had hurt him.

On Nov 25, 2015, he asked her to watch a movie with him but she replied that she had already seen it with someone she met on Tinder.

After this, he sent her multiple text messages, until she finally relented the next evening and agreed to buy dinner for him.

Ms Soh made her way from her Bishan home to Neo's Boon Lay Drive flat to deliver a packet of food, but they began quarrelling along the common corridor.

Neo's mother, Madam Ng Lian Kee, 62, who heard the commotion, came out of the flat and told him to let her leave.

But Neo snatched away Ms Soh's mobile phone and hid it inside the flat. He also took a folding knife from his bedroom and hid it behind his back.

On seeing the knife, Madam Ng tried to wrestle it away from her son.

But Neo swung the knife at Ms Soh, stabbing her once in the neck.

A neighbour called the police, while Neo threw the knife down the rubbish chute. He gave himself up when police arrived.

Ms Soh was taken to the hospital but was pronounced dead three hours later.

The knife was later recovered by police.

The punishment for culpable homicide is life imprisonment and caning, or up to 20 years' jail, with caning or a fine.