Judge says the case highlights possible flaws in two-way permit system A former PLA soldier-turned serial killer was yesterday jailed for life after murdering two prostitutes and attempting to kill a third. Zeng Xianzuo, 37, used a towel to strangle Fok Sau-king, Mao Chunyan and Pang Guiying, after having sexual intercourse with them in Shamshuipo between December 2003 and January last year. Fok and Mao's bodies were found in their flat, but Pang was saved after being resuscitated in hospital. Madam Justice Clare-Marie Beeson at the Court of First Instance yesterday sent the defendant to a life term, with a minimum fixed sentence of 20 years for one count of attempted murder. She said Zeng had committed a heinous crime and the consequence of a repeat offence would be 'injurious' to society. The court was required by law to jail him for life for each of his two convictions of murder. The judge urged a review of the two-way permit system after raising concerns that the defendant and all the prostitutes in the case had breached their conditions of stay on a two-way permit. She added it was time to consider the possibility of repatriating mainland offenders to serve their sentence on the mainland in view of the number of those who have committed crimes across the border. Zeng, who came two years ago from Guangxi on a two-way permit and operated an illegal hair salon in Yuen Long, pleaded guilty to the three charges on Wednesday after denying them at the beginning of the trial. He had served four years in the People's Liberation Army. The mainlander admitted to the police that he recalled being cheated and robbed by prostitutes in Shenzhen when he was with the three victims. The criminal act, he said, was a revenge. 'When I thought of those things I felt violent. I hated those prostitutes, who took the initiative in finding me,' he said, adding that he had developed a special hatred of women from Hubei . In her evidence, 39-year-old Ms Pang of Hubei, said Zeng told her after they had sex on December 4, 2003, that he found it 'hard to bear' that a man was picking up his wife after work every day. Pang later felt him winding a towel around her neck twice before pulling it hard. She passed out and was sent to hospital. Alexander Kee Keah-yeong, officer in charge of the case from the Kowloon West Regional Crime Unit, yesterday said serial killer cases were extremely rare in Hong Kong. He said medical examinations indicated that Zeng had no major psychiatric problems. The police team broke the case in less than 10 days in January last year. Mr Kee said Zeng was identified by his phone number in the victims' phone records and, subsequently, pieces of their belongings in his Zhuhai residence. He would return to Zhuhai from time to time.