A HEADMASTER suspected of taking money from his school strangled the accounting clerk and then burned her body, the High Court heard yesterday. But as Wong Sai-ming, 52, headmaster of the Good Shepherd Primary School in Mau Tau Wai, was setting fire to Lau Yung-mui, two passers-by saw the flames and called police, the court was told. As he tried to escape in his car, he knocked down a policeman, jurors heard. Wong, while allegedly admitting killing 41-year-old Lau in his statements to police, has pleaded not guilty to murder and is being tried by a jury before Mr Justice Leong. Prosecutor Wayne Moultrie said Wong was the headmaster of the school's morning session while Lau was responsible for the school accounts. In the middle of last year, he said, the board of directors of the school became concerned about the state of the accounts. Receipts were missing and suspicion fell on Wong. He was questioned on July 9, but was unable to produce the receipts and the board decided that he be relieved from duties from July 13, he said. The board asked Wong and Lau to attend a board meeting that day, July 13. Wong came to the meeting at 11 am, but Lau never arrived. The Crown claims that Lau was killed by Wong earlier that morning. It says Wong and Lau met in the school conference room at about 8.15 am. They talked and a struggle took place during which Wong struck Lau several times on the head with a piece of concrete before strangling her, the court heard. Wong had then hid her body in the conference room. Later that day he bought various items, including two pails of petrol, a saw and a trunk to help him dispose of Lau's body, the prosecutor said. Later that evening, the court was told, Wong put Lau's body in the trunk, placed it in the boot of his car and drove to a car park in Quarry Bay. ''There he doused the trunk with petrol and set fire to it and the body of the victim,'' Mr Moultrie said. When two passers-by saw the flames and alerted the police, the court was told, Wong drove away against the flow of the traffic for some distance without switching on the lights of his car. During his getaway, Wong knocked down a policeman and collided with a taxi, Mr Moultrie said. After Wong's arrest, the court heard, he made five statements to the police, admitting killing Lau. During the trial, Mr Moultrie said, the jury might be asked to consider the question of provocation. The Crown's case was that Wong had a motive in the killing as he had been taking money from the school accounts and Lau took care of the relevant accounts. The Crown said if there was provocation, it was insufficient to justify his action because he intended to kill Lau to cover his tracks, counsel told the court. A director of the board of directors, the Reverend Shea Tak-shun, gave evidence that on July 9 last year Wong was asked by the board to produce the receipts related to the operation of the school bus. However, he only managed to produce the receipts for 1987, 1988 and 1989, and the accounts for the years 1990, 1991 and 1992 were not available. He said Wong told the board that Lau was responsible for the receipts but when she was asked, she suggested that they might be misplaced. In view of that, Mr Shea said, the board held an urgent meeting three days later and decided to check the textbooks account as well. They also decided that Wong should go on leave the next day so that he could not disturb the account checking process. The hearing continues.