The senior prison officer found guilty of causing the death of an inmate by negligence had failed to adequately supervise his men when they were restraining the deceased, Dinesh Raman Chinnaiah, the court heard.
Lim Kwo Yin, 36, who holds the rank of deputy superintendent in the Singapore Prison Service, pleaded guilty on Friday to the charge and was fined $10,000.
The prosecution, recounting the incident of Sept 27, 2010, said Dinesh - who was serving a jail sentence for rioting and theft - had to be restrained after he had kicked a prison warden in his abdomen at about 10.45am in Changi Prison.
He was moved to a disciplinary housing unit and left alone on the ground in a "prone position" by officers under the supervision of Lim.
Lim went to check on him at about 11.18am but Dinesh did not respond and he was rush to Changi General Hospital. Doctors at the hospital pronounced Dinesh dead at 12.45pm.
A pathologist report showed that the 21-year-old was likely to have succumbed to "positional asphyxia" while being restrained. The prone position he was left in had restricted the respiratory movements of his chest and abdomen, according to the report.
Lim was also found to have failed to adequately supervise the "restraint operation".
For causing death by a negligent act not amounting to culpable homicide, Lim could have been jailed for up to two years, or fined, or both.