TWO members of a gang, who tortured a 15-year-old boy for allegedly betraying their triad ''big brother'' to the police, were jailed by the District Court yesterday. All five defendants had been found guilty of false imprisonment and wounding Wong Chiu-wah with intent. Judge Chua said the case was ''extremely distressing''. She said Wong, then 15, still bore the scars left after the defendants burned him. The five are construction site worker Kao Tai-man, then 19; transport workers Jiang Siu-fu, then 20, and Chan Kin-kwok, then 13; garage worker Mok Man-chiu, then 28; and unemployed Leung Wai-man, then 17. Although evidence showed that Kao had participated fully in the torture, Judge Chua accepted that he was not the ringleader and jailed him for three years. While jailing Mok for four years, Judge Chua inferred that he was the triad ''grandfather'' who took charge of the younger boys and subjected Wong to the ordeal. Mehboob Dosani, solicitor for Mok, said his client had nothing to say in mitigation. Judge Chua imposed a training centre order on Leung. The court heard that Wong, who had been arrested by police for a drug offence, had allegedly revealed to police the whereabouts of heroin owned by their triad ''big brother''. The defendants claimed this led to a police raid and seizure of drugs. The victim admitted he was dependent on drugs and, like the defendants, a member of a triad society. In retaliation for Wong's alleged betrayal, he was tortured for six hours. He was stripped, held down and whipped with a duster, a plastic pipe, a water hose and a leather belt. He was then forced to drink urine before strips of tissue paper were put between his fingers and toes and set on fire. Sentencing for Jiang and Chan was adjourned. Wan Chun-man, the alleged ringleader, jumped bail on February 19. Lam Chun-wah absconded on November 25.