Expert can't confirm rusty gun's link to killings
Tests were 'inconclusive' as to whether the gun retrieved from the Tsim Sha Tsui shoot-out scene last year was used in two killings in 2001, the Coroner's Court was told yesterday.
A forensics expert confirmed that the gun found under the body of off-duty constable Tsui Po-ko was the revolver of constable Leung Shing-yan, missing since Leung was gunned down in Tsuen Wan in March 2001.
But Jeffery Lloyd Chow, of the police force's forensic firearms examination bureau, said the gun had become very rusty and the grooves it made on bullets when they were fired could have changed.
'The gun was very much rusted on the outside and in the barrel,' Mr Chow told the inquest into the deaths of Tsui, shoot-out victim Tsang Kwok-hang, Leung and security guard Zafar Iqbal Khan, who was shot in a bank robbery in Tsuen Wan in December 2001.
'The rusted barrel might add extra patterns to the grooves, which made the grooves shown on bullets fired by this gun in 2006 similar, but not identical to the ones we discovered in the two incidents in 2001,' he said.
The police have been relying on the gun to link last year's shoot-out to the two 2001 killings.
Mr Chow said his examination had shown that the gun was used to kill constable Tsang in a Canton Road underpass on March 17 last year.
A specialist in examining gunshot residue told the inquest that scientific testing could not conclude that Tsui had fired with his left hand during the shoot-out. Tests done on the palm and back of Tsui's left hand and the back of his right hand showed gunshot residue, Godfrey Lee Kai-fai told the court.
'Gunshot residue can be found on a person's hand when he fires with the hand, when the hand is within a short distance from the gun, or when it has contacted something contaminated by gunshot residue,' he said.
'So it is only a possibility that he did open fire with his left hand.'
Mr Chow, who examined the underpass after the shoot-out took place, said it was quite unlikely for bullet remains found some distance from the scene to have been accidentally moved to the locations where they were found.
Constable Chan Wai-leung told the inquest earlier that two bullet jacket and bullet fragments were found inside the underpass, at least 36 metres and 75 metres from the actual scene, and he speculated they might have been kicked there by people attending the scene.
But Mr Chow said: 'The platform where the shoot-out took place stuck out from the underpass. It would have been rather difficult for the bullets to get out from it.'
Ten bullets had been fired in the shoot-out, the coroner was told. Five were from Tsang's revolver, two from Sin's and three from Leung's missing gun.
The inquest will continue on Monday.