The Jockey Club's security department is taking 'immediate measures' to ensure the integrity of drug-test samples taken from jockeys following an inconclusive inquiry into an unusual urine sample returned by jockey Eddie Lai Wai-ming. The inquiry had its origins earlier in the week when the club's head of the racing laboratory, Dr Terence Wan See-ming, informed stewards that Lai's sample, returned from routine testing at Sunday's Derby meeting, was 'somewhat unusual in appearance in that it lacked any distinguishing colour'. Jockey Club chief steward Jamie Stier said Lai supplied a further urine sample at the conclusion of the initial hearing on Tuesday. Yesterday, further evidence was taken from the jockey, as well as Dr Wan, Chan Kwan Ho (a senior security guard), and Yiu King Fung (jockeys room foreman). Firstly, Dr Wan told the inquiry that analysis of both samples was completed and that no prohibited substance was detected. Dr Wan advised the inquiry dilution tests were also carried out on these samples. The analyst said the samples supplied Lai had consistently produced low measurements in dilution tests, however, the measurements derived from Sunday sample were lower than other samples tested. He said because of the test results, he was unable to be certain the sample supplied by Lai had been adulterated. Lai, in evidence, maintained he had provided a urine sample at 5:28 pm on Sunday in the presence of Chan and no other person. He said following the provision of this sample he passed it to Mr Chan and signed the relevant sample card. Lai said he did not actually witness the splitting and sealing of the sample, however, he accepted this may have been done while he was in the sampling room. Jockey Lai did say he noted at the time of providing the sample that it 'appeared to lack colour'. Chan gave confirming evidence that Lai had provided a urine sample in his presence. He said Lai then passed the sample to him for splitting and sealing. He said he did this while Lai, standing next to him, signed the sample card and detached a portion which is sealed to the sample bottle for identification purposes. Chan said no other person had witnessed this sampling procedure. Yiu said he had been required to perform other tasks in the Jockeys Room at this time and as such he did not witness Jockey Lai's provision of the sample. He said at some time after the sample had been sealed, Chan passed him the sample card to sign as being an additional witness to the sampling process. 'The purpose of having an additional witness to the sampling process is to ensure the correct procedures are adopted and the integrity of the sample is maintained,' Stier said. 'Considering the evidence of all parties, the stewards could not be satisfied the urine sample provided by Lai had been adulterated, therefore no action was taken.' 'The security department, following a discussion with the stewards, has advised immediate measures have been taken to ensure the previously agreed sample collection procedures will be adhered to.'