THE Tuen Mun rapist, who murdered three women during a 16-month reign of terror, was yesterday described as 'a continuing and dreadful menace to Hong Kong' as he lost an appeal against conviction. Lam Kwok-wai, 23, now serving 11 life sentences, claimed the trial judge had biased the jury against him. But the Court of Appeal rejected his plea in less than an hour, deciding Mr Justice Bewley's comments at last September's High Court trial were completely justified. Lam - who was finally caught when his last rape victim invited him on a bogus date and called the police - admitted attacking lone women as they returned home late at night. In three of the 10 attacks he choked his victims to death. But Lam denied murder, pleading guilty to manslaughter on the grounds of diminished responsibility. A psychiatric report on Lam, who also admitted eight rapes and seven robberies between April 1992 and August 1993, said he had a condition which made it difficult for him to control his impulses and aggression. But the jury rejected the defence and the judge gave him life on each count of rape and murder, and seven years for each robbery. Yesterday, Lawrence Lok QC, for Lam, claimed the judge had made an 'unnecessary direction' to the jury by suggesting they would have no difficulty concluding from his police statements that he intended to cause the three women grievous bodily harm. If the jury agreed, it was up to them to decide if they accepted Lam's defence of diminished responsibility. In his confessions, Lam told how the first woman he killed, a 51-year-old supermarket worker, died after he grabbed her round the neck in a lift. He said: 'I dragged her to the rear staircase, pushed her on the floor and seized her neck with my hands until she could hardly move.' His second victim, who was 22, was killed in almost identical circumstances. Lam said he gripped her around the neck in the lift and dragged her down to the landing, where he noticed she was not moving. Mr Lok said Lam's comments did not show a clear intent to cause grievous bodily harm. But Appeal Court judge Mr Justice Power said he was confusing Lam's motive, which was rape, and his intent, which was to choke his victims into submission. Lam lost his temper with the third woman when the 23-year-old slapped him after he raped her. He said he banged her head against the wall and strangled her by mistake. Lam also failed to persuade the Appeal Court judges, Mr Justice Power, Mr Justice Ching and Mr Justice Bokhary, to reduce the eight life terms he received for the rapes. Mr Lok claimed a life sentence for rape was totally exceptional for Hong Kong and unfair as Lam might respond to medical treatment. But the court ruled life was appropriate where the defendant had a mental condition and was unstable, impulsive and aggressive. Mr Justice Bokhary said: 'The main thing is to protect the public. What sort of serial rapist would get life imprisonment if not this one?' Mr Justice Power added: 'He poses a continuing and dreadful menace to Hong Kong. 'He is wholly unable to control his sexual impulses. Furthermore, there's nothing that indicates with any certainty that he will ever respond to treatment.'