Amy Nip Life imprisonment awaits a jobless man convicted yesterday of murdering a 15-year-old part time model. After only three hours of deliberation, the High Court jury unanimously found Lau Cheung-fai, 37, guilty of murdering Kwok Wai-ming at his Mong Kok home on December 8, 2014. The killer and victim had communicated on WeChat before they met - prompting Judge Kevin Zervos to query whether social media platforms do anything to warn users of predators like Lau. The accused had pleaded not guilty to murder, offering to admit to manslaughter, but this was rejected by the prosecution. Zervos, in describing the crime as a "horrible murder," said Lau should be jailed for life according to the law, but adjourned the case to Friday, when he will give detailed reasons for sentencing. He said the defendant killed the teenage girl in an impulsive and merciless way. The trial began at the end of last year, but midway through, the defense claimed Lau was mentally unstable and unfit to stand trial. In January, the defendant was found mentally fit, and a new jury was sworn in for a retrial last month. Lau said he was upset after Kwok refused to change into clothes he had prepared during a private photo shoot at his home, so he hit the girl over the head with a bottle of ketchup. The word "blood sacrifice" came to his mind, making him strangle her and use cable ties on her neck. After the girl stopped breathing, he stuffed her into a suitcase and took it to a hotel, where he had sex with the corpse, before dumping the body at a waste collection point. Lau claimed "god" told him five times that he committed manslaughter, and that the "devil" wanted him to chop the victim up and throw her into the sea, but he did not comply. Lau was remanded to the Siu Lam Psychiatric center after his arrest. A doctor testified he was emotionally unstable and showed autistic signs, but was mentally sound. He only mentioned the devil two years after they first met.