A MENTALLY retarded man was yesterday found guilty in the District Court of abducting two boys. Cheung Sik-tim, 36, had earlier pleaded not guilty to two counts of abduction of a child. The defendant had a mental age of between three and six, having been knocked down by a car when he was a child. However, Deputy Judge Duggan said Cheung had the mental capacity to form the knowledge that he had taken away the two boys from their guardians. He said there was an overwhelming inference that Cheung took steps to separate the children from their guardians. The boys were very young, open to suggestions and vulnerable, he added. The judge said Cheung separated the first victim, Tsang Kin-kay, then nearly three, from two older boys, after gaining his favour by giving the younger boy a toy. Kin-kay was then taken away for 14 hours. The second boy was taken away for 17 hours by Cheung while the child's mother was visiting a toilet in her workplace, he said. The court heard Cheung approached Kin-kay on March 15 last year while he was playing with his eight-year-old brother, Tsang Kin-man, and another boy of a similar age in a playground in Chai Wan. Cheung gave the younger child a toy and led the boys to Siu Sai Wan shopping arcade. He then made off with the younger boy. The second offence occurred on April 8 last year while Cheung was on bail for the first offence. Cheung took away Chan Chiu-kan, who was 31/2 years old, after the boy left a Chai Wan restaurant while his mother, Cheng Shui, went to the toilet. It was the defence case that Cheung, given his mental capacity, was not able to form the necessary intention to commit the offences. The accused elected not to give evidence but called medical experts on his behalf. One expert said Cheung did not understand the meaning of abduction. Another said he knew only that he was in prison because he had played with children. The Crown also called a medical expert for rebuttal. Deputy Judge Duggan remanded Cheung at the Siu Lam Psychiatric Centre until sentencing on July 15. He ordered him placed in a hostel. Earlier, defence counsel Wong Hay-yiu submitted that a hospital order was not necessary in this case, adding that Cheung had been remanded in the Siu Lam Psychiatric Centre for more than a year. Prosecuting counsel Peter Callaghan said Cheung had two previous convictions, one of which was a similar offence. He was bound over in the sum of $500 for 12 months after he was convicted of false imprisonment on March 28, 1984.