Four men convicted of involvement in the 2004 killing of a mentally handicapped security guard over a debt of HK$6,700 have launched an appeal. Lin Siu-lun, 35, and Lau Cheuk-wah, 28, were both sentenced to life in prison after being found guilty of the murder of Wong Wai-hung on March 7, 2004. Lau Ho-nam, 22, and Cheng Sze-lok, 22, were found not guilty of murder but were both sentenced to eight years for manslaughter. Their appeals centre on whether there was sufficient evidence to prove the injuries they inflicted were the cause of Wong's death. A question was also raised about whether Mr Justice Pang Kin-kee, the trial judge, had properly instructed the jury regarding how much weight to give statements made by the suspects to police. Five other people were sentenced to a variety of prison terms after being found guilty over their involvement in the torture of Wong. During the trials of the four, the prosecution had told the court that Lin and his accomplices had hit Wong with a mop handle, folding chair, knife handle and clothes hanger over two to three weeks. The mop handle and chair were broken during the beatings. The badly beaten body of 27-year-old Wong was found dumped in Wah Shun Street, Hung Hom. A postmortem examination revealed more than 100 wounds on his back alone. The court heard that most of those wounds were received during a two-hour beating involving the folding chair. Lin had told the police that Lau, who was tried separately because of ill health, had 'spiked' Wong in the back with the handle of a knife more than 30 times. The Court of Appeal, comprising Vice-President Michael Stuart-Moore, Justice of Appeal Frank Stock and Mr Justice Michael McMahon, reserved its decision to a later date.