Martin Tan Chye Guan, dubbed the "heartbeat molester", was sentenced to 10 years' jail and 21 strokes of cane on Friday.
Singapore's worst-ever serial molester was charged in court for molesting 28 girls, aged seven to 12, between February 1999 and October 2010.
The 48-year-old Tan was found guilty of molesting young schoolgirls on staircase landings across different housing estates including Hougang, Tampines and Woodlands.
He would approach lone girls at void decks of lift lobbies and pretend to ask for directions to a non-existent flat with a made-up unit number.
While his victim led the way, he would stop and pretend he needed to rest. He would then get the victim to place her hands on his chest to "feel" his heartbeat while he moved his hands down to his other body parts.
He was diagnosed with paedophilia by the Institute of Mental Health. The court also stated that Tan was "a risk to non-acquainted female children especially those in primary school" and would "most likely adopt a predatory approach in identifying suitable victims who are alone".
Deputy Public Prosecutor Agnes Chan pointed out that Tan was clearly a risk and danger to the society and needed to be kept out of the public for the safety and interests of the public.