A former property agent killed his pregnant wife and four-year-old daughter because he "lost it" after being provoked when his wife belittled him in front of the girl, his lawyer argued in the High Court last Friday.

In arguing that Teo Ghim Heng, 44, should be found guilty of culpable homicide instead of murder, Mr Eugene Thuraisingam said his client snapped as a result of his depression and the "grave and sudden provocation".

But Deputy Public Prosecutor (DPP) Han Ming Kuang argued that the methodical manner in which Teo strangled his wife and daughter in January 2017 showed that he did not lose self-control.

Moreover, Teo's daughter was playing with her toys and watching TV at the time and had clearly not provoked him, the DPP said, in response to the defence's argument that the girl was "an active participant in the provocation" as she witnessed her father's shame.

The DPP also argued there was no objective evidence to corroborate Teo's self-reported symptoms of depression.

Justice Kannan Ramesh reserved judgement after hearing the arguments and will give his decision at a later date.

The murder charges carry the mandatory death penalty.

A third charge of killing his unborn son has been stood down for now.

Teo and Madam Choong married in 2009, it was the second marriage for both.

After he caught her with another man in their bedroom in 2014, Teo began harbouring suspicions that Zi Ning was not his biological daughter.

Teo, who used to earn $20,000 a month as a real estate agent, saw his income drop when the property market cooled. In late 2016, he took on another job as a sales coordinator with a renovation company.

The family's expenses remained unchanged and with Teo's weakness for gambling, he became mired in debt. This led to frequent quarrels.

School fees overdue 

On the morning of Jan 20, 2017, Teo decided not to send Zi Ning to school as her fees were overdue. On learning this, Madam Choong berated Teo for being useless.

Incensed, he strangled her with a towel and then with his hands. He decided to kill Zi Ning in the same way.

Teo said in court that Zi Ning was his "dearest" and he did not want her to live without her parents.

Although he admitted to the killings, Teo argued that his major depressive disorder diminished his responsibility for his acts and that he lost control due to provocation.

Last Friday, Mr Thurasingam said the trigger for depression was Teo's "fall from grace" from a successful property agent to a mere employee. Teo had told private psychiatrist Jacob Rajesh that he felt worthless, had insomnia and suicidal thoughts.

Madam Choong's barbs on the fateful day, in the presence of Zi Ning, "undermined his manhood", the lawyer argued.

The DPP contended that Madam Choong had used such hurtful words in past quarrels, and this did not amount to grave and sudden provocation.

The DPP argued that government psychiatrist Derrick Yeo had considered the relevant evidence in concluding Teo was not suffering from depression.

This article was first published in The New Paper. Permission required for reproduction.