SINGAPORE, March 27 — He diagnosed Leslie Khoo Kwee Hock with intermittent explosive disorder, but said that he would not know for a fact if Khoo was suffering from it when he killed his alleged ex-lover.
This was what Khoo’s private psychiatrist, Dr Ken Ung Eng Khean, told the court when he took the stand yesterday.
Khoo is on trial for the past two weeks, accused of strangling Cui Yajie, a 31-year-old Chinese engineer, to death at a secluded spot in Gardens by the Bay East in Singapore.
The 50-year-old does not deny murdering Cui on July 12, 2016, but his defence is that he has intermittent explosive disorder — an impulse-control condition that might have caused him to lose control of his actions on the day he killed her.
This would substantially impair his mental responsibility for his actions.
Yesterday, during a cross-examination that lasted more than three hours, Deputy Public Prosecutor (DPP) Tan Wen Hsien sought to prove that Khoo never had the disorder — a finding made by the prosecution’s psychiatrist Kenneth Koh.
The prosecution’s case is that Khoo, under pressure to keep Cui from exposing his numerous lies about his marriage and job, killed her to cover his tracks. Cui had also been asking him to return half of the S$20,000 (RM60,200) she had lent him for “investment” purposes.
Court has to decide
In his report prepared on Sept 19, 2018, Khoo’s psychiatrist concluded that there was a causal link between the disorder and Khoo’s offence, which meant that the disorder contributed to the murder.
However, whether or not Khoo snapped and lost control is a finding for the court to make, he said yesterday.
DPP Tan took Dr Ung through several criteria to be met when diagnosing someone with intermittent explosive disorder.
The psychiatrist either had to prove that Khoo had episodes of verbal assault twice weekly on average for three months, or had more severe destructive episodes at least three times within 12 months.
Dr Ung noted that Khoo’s wife, Toh Lee Nah, told him during a phone call that he was verbally aggressive to her “a few times a week for a long period of time”.
Toh did not specify the timeframe, but her evidence that Khoo’s outbursts were “long-standing” showed that he met the criteria, Dr Ung said.
Khoo and his wife first met in 2000, and she took out a personal protection order against him two years later for physically hitting her.
Toh also told Dr Ung that Khoo “got better” after his release from prison in 2012 for cheating offences. However, Khoo — a retail outlet manager at laundry firm Dryclyn Express — would shout at his co-workers if he were unhappy with their standard of work.
At work, he once kicked a partition wall that left a hole, and also threw a pen at the wall in anger while on the phone with a colleague.
Dr Ung told the court that this fulfilled both criteria — and only one is required.
Khoo also told Dr Ung that he “witnessed considerable violence as a child”, such as his mother chasing his father around with a chopper, his mother threatening Khoo with a chopper, and his parents giving him “regular physical beatings”.
Another criteria was whether Khoo’s outbursts at work were “grossly disproportionate” to what precipitated his reactions.
When DPP Tan said that Dr Ung could not come to this conclusion because the psychiatrist did not know the “context” of Khoo’s interactions with his colleagues, Dr Ung countered that shouting at them, kicking the partition wall and throwing the pen were disproportionate in “normal day-to-day scenarios”.
‘A humiliating barrage’
Earlier in the trial, Khoo testified that he often tolerated Cui’s constant berating. DPP Tan asked Dr Ung if that meant Khoo could control his impulses.
Dr Ung said that in those situations, Khoo could be able to control them even if he had intermittent explosive disorder. “It doesn’t mean every provocation will lead to outbursts,” he added.
He also said that Khoo had not displayed premeditation and did not set out “to achieve a tangible objective” — another criteria to diagnosing intermittent explosive disorder.
Dr Ung concluded this from Khoo’s account of events of “how things escalated”, where Khoo said that he pleaded with Cui not to go to his workplace, kowtowed and begged her not to expose him.
“It was the sequence of how things unfolded — what he perceived as a humiliating barrage,” Dr Ung explained.
After DPP Tan wrapped up her cross-examination, Judicial Commissioner Audrey Lim asked Dr Ung some questions.
“Just to be clear — you would not know for a fact whether (intermittent explosive disorder) was operative on the accused or manifested at the time of the offence?”
“Yes, I can’t be precisely sure, so it’s on the basis of probability,” Dr Ung replied.
“You also don’t know for a fact if the accused was provoked such that he would grab the victim’s neck, leading to her death?” the judge asked.
“I think he was provoked, from what he described to me… on the assumption that what he told me was the truth,” Dr Ung said.
“Even assuming that (intermittent explosive disorder) was operative at the time of the offence, you would not know if it substantially impaired his responsibility for the act?” the judge probed.
Dr Ung said that he would not know.
“If (an aggressor) acts to intimidate a person to prevent him or her from spilling the beans and ruining his or her business or personal reputation, would that be to achieve a tangible objective?” she asked.
Dr Ung said yes, that would be.
The trial continues today. The prosecution is expected to call three witnesses, and the court will also examine the black BMW car that Khoo drove on the day he killed Cui. — TODAY
