LOYALTY made a young man continuously pay his stepfather's gambling debts and when the sum rose to $100,000 he agreed to be a drug courier for the gambling establishment as part payment, the High Court heard. Liu Chi-kwong, 24, who was a salesman by day and a bartender by night, pleaded guilty before Deputy Judge Wong to possession of just over 100 grams of heroin for unlawful trafficking. Sentencing him to six years' jail, the judge said the mitigation ''may be a bit touching'' but stressed that the offence was serious as many people suffered because of the drug trade. Defence Counsel Mr Peter Wan said in mitigation that the stepfather was a gambler and, because of loyalty to him and his mother, Liu would give him money. The court heard that the defendant held down two jobs and, towards the end of 1990, was treated in hospital for stress. At the time, as well as providing thousands of dollars to his stepfather to settle gambling debts, Liu was supporting a younger sister studying overseas. In May 1992, his stepfather lost $100,000 in a gambling establishment. The defendant refused to help him. Mr Wan said that, on the pleadings of his mother, the defendant finally agreed to help and borrowed $50,000 from friends. He then went to the gambling establishment to ask them to accept the money as part payment and said he would repay the remainder in instalments. The offer was refused and the people running the establishment said they needed the money in cash and threatened to burn down the family home if it was not repaid. They suggested he be a drug courier, saying they would accept $50,000 and forget the rest of the debt. In addition, he would be paid $20,000 for the job. Crown Counsel Mr Michael Haselden told the court that on June 4, last year, at about 5.30 pm, police stopped and searched the defendant at Po Kong Village, Diamond Hill. He was found to be carrying a brown envelope hidden in the waistband of his jeans. It contained 11 plastic bags of No 4 heroin.