The suspects used tree branches on the youth in a revenge attack, a witness says Four men on trial for murder beat a 15-year-old boy to death in revenge for an attack on their own children, a court was told yesterday. One of the suspects later told a witness that they had beaten up the wrong person, the Court of First Instance heard. Student Cheng Chi-wai suffered severe head injuries, lapsed into a coma and died two days after the alleged attack, Senior Assistant Director of Public Prosecutions Louisa Lai told the jury. The suspects - 37-year-old Khan Janus, 24-year-old Mohammad Ahsan, and Mohammad Wasim and Khaled, both 22, have pleaded not guilty to murder. Ahsan, Khaled, who uses only one name, and Janus also have denied charges of causing grievous bodily harm with intent to kill another 15-year-old boy, Chan King-hung. The court heard that King-hung was severely injured shortly after Chi-wai was attacked. Ms Lai said the four defendants, along with about 20 other Pakistani men, ambushed a group of young cyclists near Kwong Ming Court, on Po Hong Road in Tseung Kwan O, in December 2002. The four defendants allegedly kicked and beat Chi-wai with tree branches until he collapsed. Ms Lai said 19-year-old So Chi-man, who was acquainted with the suspects and had witnessed the alleged attack, had passed on information to the police in August last year. In court yesterday, Mr So said on the night of December 7, 2002, there were about 30 Pakistani men who had gathered near Kwong Ming Court. Ahsan and Janus allegedly told him they were looking for a group of cyclists who had earlier attacked their children. When a group of cyclists arrived, Mr So said about 10 of the men rushed forward. Wasim initially threw a branch at Chi-wai, but it missed the boy, Mr So said. However, when Chi-wai stopped, Ahsan hit him on the back of the head with another branch. The boy tried to get away, but was allegedly pulled from his bicycle by Wasim. Mr So said Ahsan and Wasim subsequently struck Chi-wai with branches several times, including about the head, while the other two defendants kicked him. Mr So estimated the duration of the beating to have been less than a minute, saying the boy subsequently ran to a nearby lawn, where he collapsed. Janus, Ahsan and Khaled then attacked King-hung, Mr So told the court. 'He was lying on the ground and yelling,' he said. Ms Lai said Mr So was later told by two of the defendants that they had beaten up 'the wrong guy'. The trial continues today before Mr Justice Thomas Gall.