The fates of several former drug abusers now hang by a hair - their own.
Since May, the Central Narcotics Bureau (CNB) has been analysing hair samples from ex-drug abusers currently serving out their compulsory two-year supervision order.
By using hair, the CNB can detect drugs in the body even months after use, as compared to the usual urine tests, which are effective for just a week.
While the CNB is starting small with 15 currently on the programme, it aims to include 100 ex-offenders by the end of next year, before eventually making it a bigger weapon in the war on drugs.
"In the long run, we want to be able to use it (hair analysis) in court for prosecution," said deputy director Michael Neo of CNB's supervision division.
The agency started working with the Health Sciences Authority to build up its hair-analysis capabilities last year, ahead of changes to the Misuse of Drugs Act which allows the use of the new test starting this year.
Going bald is no escape.
Ex-offenders on the programme must maintain at least four centimetres of hair, which cannot be cosmetically treated by colouring or perming for instance.
Every third month, they have to provide hair samples when reporting at CNB's supervision centre at Cantonment Complex, while urine samples are given monthly.
In comparison, the majority of drug offenders who have served their time have to provide urine samples either once or twice a week.