He was on his way home on Tuesday at 10.30pm when he spotted a man disposing small cans of paint in a rubbish bin on Bukit Batok West Avenue 4.
Sensing something amiss, the off-duty officer immediately called for reinforcement and detained him.
Following an interview, the man, 47, was arrested for suspected involvement in loansharking harassment.
Loansharking-related items like paint, paint remover and gloves were found in the suspect's possession.
Police believe he is a debtor-turned-harasser, who assisted loanshark syndicates in harassing debtors.
He was charged on Wednesday.
If convicted, he can be jailed for up to five years, fined up to $50,000 and given up to six strokes of the cane.
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