All 4 psychiatric experts opined that convicted drug mule Nagaenthran K. Dharmalingam was not intellectually disabled.

According to court documents seen by Fathership, 4 psychiatric experts gave their reports and testimonies on Nagaenthran's mental health assessment.

While all of the 4 psychiatrists agree that Nagaenthran has borderline intelligence, he was not mentally retarded.

Psychiatrists appointed by the prosecution

• Two psychiatric reports from Dr Koh Wun Wu Kenneth Gerald dated 11 April 2013 and 7 February 2017.

Dr Koh is a senior consultant from the Department of General and Forensic Psychiatry at the Institute of Mental Health (IMH)

• A psychological report from Eunice Seah dated 12 April 2013.

Eunice is a psychologist at IMH's Department of Psychology

• A psychiatric report from Dr Patricia Yap dated 1 February 2017.

Dr Yap is the Principal Clinical Psychologist at the IMH.

Psychiatrist appointed by Nagaenthran's legal defence team

A psychiatric report from Dr Ken Ung Eng Khean dated 22 August 2016.

Dr Ung is a psychiatrist from Adam Road Medical Centre.

Dr Koh's 2013 report

Nagaenthran was examined Dr Koh on 14 and 21 March 2013. Nagaenthran's sister was also interviewed by Dr Koh over the phone, as well as his prison officer.

Dr Koh's opinion:

Mr Nagaenthran had no mental illness at the time of the offence. Although not clinically mentally retarded, his borderline range of intelligence might have made him more susceptible than a person of normal intelligence to over-estimating the reality of the alleged threat that had been made to his girlfriend if he refused to make the delivery of the drugs. It, however, would not have diminished his ability to appreciate that the package that was taped to his thigh would most likely have contained drugs and that bringing this to Singapore was illegal.

Eunice Seah's 2013 report

Seah assessed Nagaenthran on 4 April 2013. She conducted first an interview followed by two psychometric measures. She also conducted the 'Test of Memory Malingering (TOMM)'. Nagaenthran's sister was also interviewed.

Seah's opinion:

In view of Nagaenthran’s performance on the various WAIS-IV (Wechsler Adult Intelligence Scales (Fourth Edition) indexes, socio-occupational history, education history, his adaptive functioning abilities and his presentation during the assessment, Nagaenthran is functioning at least within the Borderline range of functioning and he is assessed not to be intellectually disabled.

Dr Ung's 2016 report

Nagaenthran's then lawyer Eugene Thuraisingam appointed Dr Ung to conduct a separate psychiatric assessment.

Dr Ung assessed Nagaenthran on 19 April and 19 July 2016 and also relied on the findings made in Dr Koh's 2013 report.

Dr Ung's opinion:

I am of the opinion that Mr Nagaenthran suffered from an abnormality of mind at the time of his arrest, namely: Severe Alcohol Use Disorder, Severe Attention Deficit Hyperactivity Disorder ADHD) [sic] Combined Type and Borderline Intellectual Functioning/ Mild Intellectual Disability.

(Nagaenthran's IQ) is revealed to be 66 to 74. This is in the range of Mild Intellectual Disability suggested by the [the American Psychiatric Association]

Intellectual Disability requires the presence of functional disability as well and I am of the opinion that Mr Nagaenthran had functional disability in the conceptual domains and to a lesser extent in his social and practical domain.

Dr Yap's 2017 report

In light of Dr Ung’s Report, the applicant was referred by Dr Koh to Dr Yap for the purposes of conducting a neuropsychological assessment to explore the possibility that the applicant was suffering from ADHD.

Dr Yap conducted 7 assessments totalling 15 hours and 55 minutes in the period November 2016 to January 2017. 18 psychometric tests as well as a one-hour interview with Nagaenthran's sister on 29 December 2016.

Dr Yap's conclusion:

The results indicate that Mr Nagaenthran is not intellectually disabled...Additionally, testing revealed that while many of Mr Nagaenthran’s executive functioning skills were impaired, he was able to plan and organise on simpler items and there were no indications of problems with impulsivity and vigilance.

While there are some indications in the current assessment that Mr Nagaenthran may have adult ADHD, his account of the incidents leading to his arrest suggests that he acted in a pre-meditated fashion and understood the potential consequences of his behaviour.

Dr Koh's 2017 report

In a report dated 7 February 2017, Dr Koh made a few observations in response to the conclusions drawn in Dr Ung’s Report.

First, Dr Koh disagreed with Dr Ung that the applicant was mildly intellectually disabled.

The conclusions drawn in Dr Yap’s Report about the applicant’s intelligence are in agreement with those reached in Ms Seah’s Report: both Dr Yap and Ms Seah had concluded that the applicant was not intellectually disabled.

Second, Dr Koh rejected Dr Ung’s diagnosis that the applicant had ADHD. Dr Koh called into question Dr Ung’s reliance on the Adult ADHD Self-Report Scale (“ASRS”), given that the ASRS is a self-rating scale that carries the attendant possibility of bias. Dr Koh suggested that Dr Yap’s employment of the more objective Connor’s Continuous Performance Test (3rd Edition) (“CPT3”) was more instructive.

Dr Koh’s opinion was that even if the applicant has ADHD, his condition is mild, with features of inattentiveness, but not hyperactivity or impulsiveness.

Third, Dr Koh questioned Dr Ung’s diagnosis of severe alcohol use disorder, given that the applicant’s account of his alcohol use to Dr Ung greatly differed from that provided to Dr Koh when he was preparing his 2013 psychiatric report.

Dr Koh also acknowledged that the applicant’s “borderline intelligence and concurrent cognitive defects may have contributed toward his misdirected loyalty and poor assessment of the risks in agreeing to carry out the offence [that he was convicted for]”

Defence's psychiatrist initially suggested that Nagaenthran had intellectual disability but later admitted the contrary when cross-examined

Dr Ung's report had suggested that Nagaenthran suffered from mild intellectual disability:

I am of the opinion that Mr Nagaenthran suffered from an abnormality of mind at the time of his arrest, namely: Severe Alcohol Use Disorder, ADHD and Borderline Intellectual Functioning / Mild Intellectual Disability.

Intellectual Disability requires the presence of functional disability as well and I am of the opinion that Mr Nagaenthran had functional disability in the conceptual domains and to a lesser extent in his social and practical domain.

According to the court documents, Dr Ung later agreed during cross-examination, with Dr Yap's opinion that the applicant is not intellectually disabled.

Conversely, Dr Koh, Ms Seah and Dr Yap all opine in their respective expert reports that the applicant is not intellectually disabled, and merely suffers from borderline intellectual functioning.

Dr Ung's psychiatric report was highlighted by the judge to carry a tendency of bias and could not stand to scrutiny.

The judge also found Dr Ung's methodology and assessment of Nagaenthran to be unreliable.