Clutching an alarm in her handbag and a bunch of keys in her hand, policewoman Debby Chan Sau-wan stood in the lift lobby of a Tuen Mun public housing block hoping to keep a date with a serial rapist and murderer. She was waiting as part of an undercover operation in an effort to catch a serial rapist preying on lone, long-haired women returning home late at night. Decoration worker Lam Kwok-wai - the notorious Tuen Mun rapist - is now serving 11 life sentences. He attacked 10 women in 1992 and 1993 when in his early 20s, raping eight of them. The other two were strangled, as was one of the rape victims. Ten years on, Inspector Chan has spoken in detail for the first time about how she acted as human bait in the operation aimed at ending Lam's 16-month reign of terror. Her testimony will be featured in the RTHK TV programme On the Beat , to be screened at 7pm on TVB Jade tonight. Inspector Chan - who failed in her efforts to confront the rapist - was a constable when she was approached to set the trap. She was told that several other officers had already refused. 'I was told that a victim had died and several others had been raped. I was shown the photographs of the victims. I was told that I could die or be paralysed in the operation. I was very, very scared, but I agreed to take up the job. If police officers did not do it, nobody else would,' she said. Inspector Chan and two other female officers underwent training, including how to protect themselves. 'We applied baby oil to our necks so that even if we were strangled, the oil might help reduce the force,' she said. 'Whenever we stepped into the lift, we moved to a corner so that we could give the culprit a forceful kick if we were attacked.' The officer was also equipped with an alarm and a bunch of keys, which she interlaced between her fingers with the sharp ends pointing outwards. Inspector Chan, who had short hair then, also had to wear a wig. To minimise the time they needed to be with the culprit alone in the lift, Inspector Chan said she would press the button for the lowest floor, with colleagues ready to spring into action whenever the lift doors opened or the alarm bell sounded. Inspector Chan and the two other 'baits' took turns to take the lift at different housing estates in Tuen Mun every night for three months between 11pm to 6am. As regards the operation, involving more than 100 officers, sergeant and case analyst Chan Yuet-keung said every detail was analysed, even the tidal factor, to try to work out the possible time and place of the next attack. Recalling the operation, Inspector Chan said: 'I thought I would meet the culprit and die. The sky was so dark in my head.' After weeks waiting for the rapist, she was told that another victim had been killed. 'I was shown the photograph of the victim. I told myself that there would be no more,' she said. But the operation was abandoned when it was found the culprit was attacking women outside Tuen Mun. Lam was arrested in August 1993 when his last victim - who had earlier been raped by him - invited him on a bogus date and called police.