The DNA on the mask lying near the body of the slain constable, Leung Shing-yan did not match with Leung's, the coroner court was told yesterday.

The inquest into the death of Leung, a Pakistani security guard Khan Zafar Iqbal, constables Tsang Kwok-hang and Tsui Po-ko, allegedly the key person behind the killings, might face uncertainty as legal representative of Tsui's mother, Cheung Wai-mei, was considering applying for judicial review against certain legal procedure application should there be financial assistance.

The inquest was adjourned on Monday as Cheung's representative Arthur Yip Chi-ho made the legal procedure application to coroner Michael Chan.

Yip said yesterday his client had asked him not to attend the inquest until the hearing proceeds to last year's Tsim Sha Tsui shoot-out, in which Tsang and Tsui were killed.

Solicitor helping Cheung, Wong Kwok-tung, had submitted an application to the Department of Justice for waiving the judicial review fees, citing public interest as the reason.

The judicial review, concerning the legal procedure of the inquest, would be a financial burden on Cheung should the fees waiver was turned down. Wong estimated the cost could be more than HK$100,000.

"We may not proceed to apply for judicial review if we cannot get the fees waiver," he said.

Yip said the inquest might not be adjourned even though they had applied for judicial review.

Police had collected material evidence, including tissues and the mask, found at the crime scene in Shek To House, Shek Wai Kok Estate for analysis.

Forensic scientist Cheung Kam-yin said the DNA on the mask did not match with Leung's, and the mask belonged to an unknown person.

The DNA sample of that unknown person was found at the mask front side bottom, and every 44 men in Hong Kong would have the same feature.

Such DNA sample also matched with those found at the middle of the mask's back side.

However, the test did not reveal the identity of that unknown man, and whether the mask belonged to Tsui, who allegedly killed Leung and Khan in 2001 and Tsang in 2006.

However, if the police had identified the culprit and collected his DNA sample, the test results could be comparable, Cheung added.

Government scientific evidence officer Lam Tak-keung said in a written testimony presented to the court last Friday that the mask was suspected to belong to the culprit.

Cheung had also found the DNA samples of another person from the blood stain collected from the scene.

Cheung had also attempted to collect DNA samples from Leung's fingernail as Leung might have struggled with the culprit, but such features were not found.

Police officer Tse Ka-hung testified that the police had arrested six persons, but later released them as their DNA samples did not match with those found in the material evidence.

He said the three rubbish bags found in the scene contained soft drink cans and food leftover, which were not related to the case.

Cheung, pathologist Lam Wai-man and ballistic forensic expert Leung Sai-leung will give testimony today.