A day before he strangled his pregnant wife and four-year-old daughter, former property agent Teo Ghim Heng visited an online sex forum 132 times.
Teo was a frequent visitor of Sammyboy Forum in the weeks leading to the killings, which government psychiatrist Derrick Yeo said cast doubt on whether he showed symptoms of depression.
The issue of whether Teo, 43, was suffering from major depressive disorder (MDD) was hotly debated in the High Court yesterday.
He faces the death penalty on two counts of murder for strangling his wife Choong Pei Shan, 39, and their daughter Zi Ning, at their Woodlands flat on Jan 20, 2017.
The defence, relying on a report by private psychiatrist Jacob Rajesh, said Teo had MDD and the condition reduced his mental responsibility for the killings.
Dr Rajesh's report said Teo had symptoms of depressed mood, poor sleep, a constant sense of worthlessness, low self-esteem and hopelessness. The disorder was brought on by his mounting debts and sense of helplessness.
But Dr Yeo, who is from the Institute of Mental Health, said Teo did not have any mental disorder and he was optimistic he would be able to turn his fortunes around.
Deputy Public Prosecutor Han Ming Kuang said Teo surfed the sex-themed forum almost every day between Dec 1, 2016 and Jan 19, 2017. On the eve of the killings, Teo visited it 132 times.
Dr Yeo said the fact that Teo was enjoying pornography regularly "cast an objective doubt" over whether he showed a loss of interest in all activities, one of the symptoms of MDD. He added that while Teo had some symptoms, none were clinically significant.
Dr Yeo also did not place much weight on Teo's claim of having had suicidal thoughts for a year.
If Teo was really suicidal, he would have jumped over the parapet when the police were at his door, said Dr Yeo.
After killing his wife and daughter, Teo watched TV, ordered food on McDelivery and surfed the Net for ways to commit suicide.
He set fire to the bodies and laid next to them in a suicide attempt, but later left the flat as there was a lot of smoke. He also concocted lies to his family and his in-laws in the days after the killings. This showed "clarity of thought" and "very clear planning", said Dr Yeo.
Teo also told both psychiatrists that Madam Choong had an extra-marital affair. He said that in 2014, he came home to find the man in his bedroom. He suspected Zi Ning was not his biological daughter.
Teo's lawyer Eugene Thuraisingam said Teo, once a successful property agent, had "fallen" in status to renovation firm employee. He cited anecdotes that Teo looked like a "different person" in January 2017 and wore the same shirt to work on most days.
The trial has been adjourned. Hearing dates have yet to be fixed.