DETECTIVES searching for missing schoolgirl Ng Lai-ping yesterday admitted they had given up hope of finding her alive. Officers are now studying the files of known sex attackers in the hope of finding a link. In the meantime, all search parties have been called off. The team spent last week liaising with the Organised Crime and Triad Bureau which recently reopened a 10-year-old investigation into the murder of Sha Tin schoolgirl Ng Hoi-lam. The eight-year-old was reported missing on July 2, 1983, when she vanished from a playground outside Lek Yuen Estate, a few metres from her home. Her skeleton was discovered 18 months later. Police have a suspect they believe may also be responsible for crimes stretching back more than 20 years. But police cannot charge the man due to lack of conclusive evidence. ''There are similarities between both cases,'' said Detective Chief Inspector Wong Tat-wah of the Shamshuipo District Crime Squad. ''Both were young, intelligent girls and both appear to have been lured away from busy areas.'' Lai-ping has been missing since November 2 but, apart from four vague sightings, there have been no leads. Police say it was strongly possible she was sexually assaulted and then killed by her abductor after being lured from her shopping trip to Tsim Sha Tsui. ''We have had four sightings of Lai-ping but they were all made within days of her disappearing. We have heard nothing since and have very little to work on. ''We fear for the worst. Sweep searches have been called off because, without fresh information, we do not know where to look. It is like trying to find a needle in a haystack. She could be anywhere.'' Officers working on the case said it was highly unlikely Lai-ping had run away from her home in Chak On Estate, Shamshuipo. She had arranged to meet a male classmate at the Haiphong Road MTR exit in Tsim Sha Tsui at 2 pm but did not turn up. The last positive sighting was at 2.42 pm on November 2 in the Hong Kong Pacific Centre, Hankow Road, where she had taken an electronic dictionary to be repaired. Her father Ng Wai-chuen said he still hoped his daughter could come home one day even though ''I know it may only be a dream''. ''I know our hopes are fading. I only hope she can be the lucky one. What else can I do?'' he asked. Mr Ng thought there was a possibility his daughter had been kidnapped and taken out of the territory. ''I think the police would have discovered her if she was still in Hong Kong. I am just afraid she was transported overseas.''