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.
"With hair analysis, we subject them to fewer reporting times, so it becomes less disruptive to their lives, and they can reintegrate back into society better," said Mr Neo.
At the same time, the bureau can make better use of manpower, he added.
Any breach of the rules or a positive test will land the former drug abuser back on the stricter urine regime.
Hair samples tell the CNB more than urine can.
Depending on where drug traces along a strand of hair are found, scientists can determine consumption habits, such as if a person was a habitual or infrequent drug abuser, and roughly when the drug was consumed.
"Hair has a higher level of permanence: drug metabolites get trapped inside the hair follicle and will grow out together with the hair," explained Mr Tan Seow Keong, the senior officer-in-charge of CNB's "A" Supervision Division.
An early challenge the bureau faced was how to procure the hair samples without leaving visible bald spots, said Mr Neo.
On a study trip to South Korea, where hair analysis is an established practice, Mr Neo said officers would cable-tie a portion of the hair and simply snip it off, with no consideration for how this would affect the suspect.
"One of the main challenges was how we could train our officers to cut it in a better way, so that it would minimise this kind of unpleasantness to the supervisee," he explained.
The answer was to tie up with a hairstyling school.
Officers tasked to take hair samples are taught to snip them from multiple spots on the head, using hairstyling tools such as beak clips and a highlight comb to minimise any visual impact.
For former drug abuser Mary (not her real name), the mild unpleasantness of chopped locks has been a small price to pay for greater freedom.
The cleaner was caught after being persuaded by her boyfriend to take heroin. After her release from prison in April, the single mother had to report for urine tests every Monday and Friday, which negatively affected her work.
"I had to rush to the reporting centre, to work, and then to my daughter's school and when I asked for time off, my supervisor would get angry at me and say 'Monday you off, then Friday you want off'," said the 34-year-old.
"Now I have more time, and I don't need to rush."