TUEN Mun residents have called on the police to step up patrols in public housing estates while a serial rapist, believed to have attacked at least five victims over the past year, is still at large. The most recent victim was a 50-year-old woman who was raped and murdered in a block at Yau Oi Estate in February. But a police manhunt has failed to quieten residents' fears. A women's safety concern group, led by district board members Ms Cheung Yuet-lan and Ms Ho Hang-mui, petitioned legislators yesterday. They claimed police inefficiency meant the man was still free. Tuen Mun District Board is expected to pass a motion during a meeting next Tuesday urging officers to heighten investigations. Board member Mr Ng Wai-cho said: ''Police did step up patrols for a while. Yet, we seldom see police patrolling now.'' His colleague Ms Cheung Yuet-lan added: ''It seems the police just wanted to stage some show to calm down residents whenever there was an incident. But we need concrete action.'' Ms Cheung also called on the Housing Department to change the designs of estate lobbies to ensure security. ''The so-called open-door design is a major shortcoming. There is no caretaker to check visitors nor is there a gate to prevent strangers from entering the block,'' Ms Cheung said. She suggested the installation of emergency telephones and closed circuit televisions at lift lobbies. Tuen Mun district chief inspector Leung Po-tak said patrols had been stepped up since February. He said: ''We do have a minor manpower problem but our efficiency has not been affected.'' There were 16 rapes and 88 indecent assaults in Tuen Mun last year.