Police yesterday published a sketch of the alleged sex attacker involved in an indecent assault and two other attempted attacks against schoolgirls at a Kwai Chung public housing estate. The drawing was done after the 15-year-old assault victim identified the man as her assailant from images captured on security cameras at Lai Yiu Estate, where she was attacked on Tuesday. The Cantonese-speaking man is described as aged between 20 and 25, about 1.7 metres tall, thin, with a dark complexion. He was wearing a blue and white T-shirt and light-brown trousers when he attacked the girl. Officers believe the man likes to prey on girls in school uniform and may live on the same estate because he appeared to know the area well. Yesterday, Kwai Tsing district crime squad stepped up surveillance at the estate and handed out the sketch of the suspect to residents on the estate. Superintendent Chan Kwok-keung, assistant Kwai Tsing district commander (crime), said investigators had not yet identified the man and appealed to the public to provide information they think is relevant. The schoolgirl was attacked on a staircase of the estate's Kwai Yiu House after school at about 4pm on Tuesday. Two other schoolgirls, aged 12 and 15, were both grabbed earlier this month when they walked out of lifts in another block of flats on the same estate. Police said that on both occasions, their attacker fled when the girls shouted for help. Officers believe the same man was involved in all three incidents because the victims' descriptions of their attacker were similar. Anyone with information should call officers from Kwai Tsing district crime squad on 2410 2359 or 2410 2200. Meanwhile, detectives in Wong Tai Sin were looking for another sex attacker who posed as a police officer and assaulted a nine-year-old girl on the roof of a community centre in Fung Tak Estate on Thursday night. The man approached the girl while she waited to attend private tuition outside a classroom at the community centre at about 7pm. The attacker, aged between 30 and 40, was about 1.6 metres tall and of medium build with short hair parted in the middle. Police said the man was wearing a black suit, white shirt and black trousers at the time of the attack. Officers said he was not believed to be the same man involved in the Kwai Chung attacks.