Rehabilitation authorities are stepping up surprise urine checks on discharged drug offenders to tighten scrutiny of potential relapses. Two former prison officers were jailed last year for falsifying specimens.
The gathering process will also be centralised at a collection centre for urine samples that will open in the middle of the year outside the Lai Chi Kok Reception Centre.
At the moment specimens are collected when rehabilitation officers from the Correctional Services Department make monthly visits to their released charges - a process that is open to fabrication, which, in turn, distorts the drug relapse rate.
As the new centre comes into operation, the department will implement stricter measures to ensure the samples are genuine, a source close to the matter says.
"This will not only find out if the people under supervision have gone back to drugs, but will also make sure the samples are not tampered with," he said.
The department now supervises several hundred former drug offenders.
Under the new measures, released inmates are required to report to the collection centre within three days of a rehabilitation officer's visit - the maximum period during which drugs in the body can be detected.
The whole collection process, except the moment they pass urine under officers' observation, will be videotaped. The samples will then undergo testing at the department's own centres or government laboratories.
That may be followed soon after by random spot checks on ex-inmates during which a supervisor of the rehabilitation division will ask them to provide urine samples again.
Two former prison officers were sentenced to three months last year for falsifying urine samples to suppress the drug relapse rate. They have appealed, claiming urine-swapping is common practice and is ordered by senior officers.