A part-time tutor used a spy camera implanted in a pen to record voyeuristic videos of fellow staff members and young students using the toilet at an education centre where he worked, doing this over three years or so.
Investigations later uncovered about 80 voyeuristic images or video recordings taken at the centre, including 24 that showed children under the age of 14.
Investigators also found out that the man had begun his voyeuristic pursuits as early as 2011, when he started by filming his own sisters using mobile phones.
On Friday, the 30-year-old Singaporean pleaded guilty to three counts of voyeurism and two of possessing voyeuristic materials.
Six similar charges will be taken into consideration for his sentencing.